Journal of Clinical and Diagnostic Research, ISSN - 0973 - 709X

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Dr Mohan Z Mani

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Believers Church Medical College,
Thiruvalla, Kerala
On Sep 2018




Prof. Somashekhar Nimbalkar

"Over the last few years, we have published our research regularly in Journal of Clinical and Diagnostic Research. Having published in more than 20 high impact journals over the last five years including several high impact ones and reviewing articles for even more journals across my fields of interest, we value our published work in JCDR for their high standards in publishing scientific articles. The ease of submission, the rapid reviews in under a month, the high quality of their reviewers and keen attention to the final process of proofs and publication, ensure that there are no mistakes in the final article. We have been asked clarifications on several occasions and have been happy to provide them and it exemplifies the commitment to quality of the team at JCDR."



Prof. Somashekhar Nimbalkar
Head, Department of Pediatrics, Pramukhswami Medical College, Karamsad
Chairman, Research Group, Charutar Arogya Mandal, Karamsad
National Joint Coordinator - Advanced IAP NNF NRP Program
Ex-Member, Governing Body, National Neonatology Forum, New Delhi
Ex-President - National Neonatology Forum Gujarat State Chapter
Department of Pediatrics, Pramukhswami Medical College, Karamsad, Anand, Gujarat.
On Sep 2018




Dr. Kalyani R

"Journal of Clinical and Diagnostic Research is at present a well-known Indian originated scientific journal which started with a humble beginning. I have been associated with this journal since many years. I appreciate the Editor, Dr. Hemant Jain, for his constant effort in bringing up this journal to the present status right from the scratch. The journal is multidisciplinary. It encourages in publishing the scientific articles from postgraduates and also the beginners who start their career. At the same time the journal also caters for the high quality articles from specialty and super-specialty researchers. Hence it provides a platform for the scientist and researchers to publish. The other aspect of it is, the readers get the information regarding the most recent developments in science which can be used for teaching, research, treating patients and to some extent take preventive measures against certain diseases. The journal is contributing immensely to the society at national and international level."



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Professor and Head
Department of Pathology
Sri Devaraj Urs Medical College
Sri Devaraj Urs Academy of Higher Education and Research , Kolar, Karnataka
On Sep 2018




Dr. Saumya Navit

"As a peer-reviewed journal, the Journal of Clinical and Diagnostic Research provides an opportunity to researchers, scientists and budding professionals to explore the developments in the field of medicine and dentistry and their varied specialities, thus extending our view on biological diversities of living species in relation to medicine.
‘Knowledge is treasure of a wise man.’ The free access of this journal provides an immense scope of learning for the both the old and the young in field of medicine and dentistry as well. The multidisciplinary nature of the journal makes it a better platform to absorb all that is being researched and developed. The publication process is systematic and professional. Online submission, publication and peer reviewing makes it a user-friendly journal.
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I wish JCDR a great success and I hope that journal will soar higher with the passing time."



Dr Saumya Navit
Professor and Head
Department of Pediatric Dentistry
Saraswati Dental College
Lucknow
On Sep 2018




Dr. Arunava Biswas

"My sincere attachment with JCDR as an author as well as reviewer is a learning experience . Their systematic approach in publication of article in various categories is really praiseworthy.
Their prompt and timely response to review's query and the manner in which they have set the reviewing process helps in extracting the best possible scientific writings for publication.
It's a honour and pride to be a part of the JCDR team. My very best wishes to JCDR and hope it will sparkle up above the sky as a high indexed journal in near future."



Dr. Arunava Biswas
MD, DM (Clinical Pharmacology)
Assistant Professor
Department of Pharmacology
Calcutta National Medical College & Hospital , Kolkata




Dr. C.S. Ramesh Babu
" Journal of Clinical and Diagnostic Research (JCDR) is a multi-specialty medical and dental journal publishing high quality research articles in almost all branches of medicine. The quality of printing of figures and tables is excellent and comparable to any International journal. An added advantage is nominal publication charges and monthly issue of the journal and more chances of an article being accepted for publication. Moreover being a multi-specialty journal an article concerning a particular specialty has a wider reach of readers of other related specialties also. As an author and reviewer for several years I find this Journal most suitable and highly recommend this Journal."
Best regards,
C.S. Ramesh Babu,
Associate Professor of Anatomy,
Muzaffarnagar Medical College,
Muzaffarnagar.
On Aug 2018




Dr. Arundhathi. S
"Journal of Clinical and Diagnostic Research (JCDR) is a reputed peer reviewed journal and is constantly involved in publishing high quality research articles related to medicine. Its been a great pleasure to be associated with this esteemed journal as a reviewer and as an author for a couple of years. The editorial board consists of many dedicated and reputed experts as its members and they are doing an appreciable work in guiding budding researchers. JCDR is doing a commendable job in scientific research by promoting excellent quality research & review articles and case reports & series. The reviewers provide appropriate suggestions that improve the quality of articles. I strongly recommend my fraternity to encourage JCDR by contributing their valuable research work in this widely accepted, user friendly journal. I hope my collaboration with JCDR will continue for a long time".



Dr. Arundhathi. S
MBBS, MD (Pathology),
Sanjay Gandhi institute of trauma and orthopedics,
Bengaluru.
On Aug 2018




Dr. Mamta Gupta,
"It gives me great pleasure to be associated with JCDR, since last 2-3 years. Since then I have authored, co-authored and reviewed about 25 articles in JCDR. I thank JCDR for giving me an opportunity to improve my own skills as an author and a reviewer.
It 's a multispecialty journal, publishing high quality articles. It gives a platform to the authors to publish their research work which can be available for everyone across the globe to read. The best thing about JCDR is that the full articles of all medical specialties are available as pdf/html for reading free of cost or without institutional subscription, which is not there for other journals. For those who have problem in writing manuscript or do statistical work, JCDR comes for their rescue.
The journal has a monthly publication and the articles are published quite fast. In time compared to other journals. The on-line first publication is also a great advantage and facility to review one's own articles before going to print. The response to any query and permission if required, is quite fast; this is quite commendable. I have a very good experience about seeking quick permission for quoting a photograph (Fig.) from a JCDR article for my chapter authored in an E book. I never thought it would be so easy. No hassles.
Reviewing articles is no less a pain staking process and requires in depth perception, knowledge about the topic for review. It requires time and concentration, yet I enjoy doing it. The JCDR website especially for the reviewers is quite user friendly. My suggestions for improving the journal is, more strict review process, so that only high quality articles are published. I find a a good number of articles in Obst. Gynae, hence, a new journal for this specialty titled JCDR-OG can be started. May be a bimonthly or quarterly publication to begin with. Only selected articles should find a place in it.
An yearly reward for the best article authored can also incentivize the authors. Though the process of finding the best article will be not be very easy. I do not know how reviewing process can be improved. If an article is being reviewed by two reviewers, then opinion of one can be communicated to the other or the final opinion of the editor can be communicated to the reviewer if requested for. This will help one’s reviewing skills.
My best wishes to Dr. Hemant Jain and all the editorial staff of JCDR for their untiring efforts to bring out this journal. I strongly recommend medical fraternity to publish their valuable research work in this esteemed journal, JCDR".



Dr. Mamta Gupta
Consultant
(Ex HOD Obs &Gynae, Hindu Rao Hospital and associated NDMC Medical College, Delhi)
Aug 2018




Dr. Rajendra Kumar Ghritlaharey

"I wish to thank Dr. Hemant Jain, Editor-in-Chief Journal of Clinical and Diagnostic Research (JCDR), for asking me to write up few words.
Writing is the representation of language in a textual medium i e; into the words and sentences on paper. Quality medical manuscript writing in particular, demands not only a high-quality research, but also requires accurate and concise communication of findings and conclusions, with adherence to particular journal guidelines. In medical field whether working in teaching, private, or in corporate institution, everyone wants to excel in his / her own field and get recognised by making manuscripts publication.


Authors are the souls of any journal, and deserve much respect. To publish a journal manuscripts are needed from authors. Authors have a great responsibility for producing facts of their work in terms of number and results truthfully and an individual honesty is expected from authors in this regards. Both ways its true "No authors-No manuscripts-No journals" and "No journals–No manuscripts–No authors". Reviewing a manuscript is also a very responsible and important task of any peer-reviewed journal and to be taken seriously. It needs knowledge on the subject, sincerity, honesty and determination. Although the process of reviewing a manuscript is a time consuming task butit is expected to give one's best remarks within the time frame of the journal.
Salient features of the JCDR: It is a biomedical, multidisciplinary (including all medical and dental specialities), e-journal, with wide scope and extensive author support. At the same time, a free text of manuscript is available in HTML and PDF format. There is fast growing authorship and readership with JCDR as this can be judged by the number of articles published in it i e; in Feb 2007 of its first issue, it contained 5 articles only, and now in its recent volume published in April 2011, it contained 67 manuscripts. This e-journal is fulfilling the commitments and objectives sincerely, (as stated by Editor-in-chief in his preface to first edition) i e; to encourage physicians through the internet, especially from the developing countries who witness a spectrum of disease and acquire a wealth of knowledge to publish their experiences to benefit the medical community in patients care. I also feel that many of us have work of substance, newer ideas, adequate clinical materials but poor in medical writing and hesitation to submit the work and need help. JCDR provides authors help in this regards.
Timely publication of journal: Publication of manuscripts and bringing out the issue in time is one of the positive aspects of JCDR and is possible with strong support team in terms of peer reviewers, proof reading, language check, computer operators, etc. This is one of the great reasons for authors to submit their work with JCDR. Another best part of JCDR is "Online first Publications" facilities available for the authors. This facility not only provides the prompt publications of the manuscripts but at the same time also early availability of the manuscripts for the readers.
Indexation and online availability: Indexation transforms the journal in some sense from its local ownership to the worldwide professional community and to the public.JCDR is indexed with Embase & EMbiology, Google Scholar, Index Copernicus, Chemical Abstracts Service, Journal seek Database, Indian Science Abstracts, to name few of them. Manuscriptspublished in JCDR are available on major search engines ie; google, yahoo, msn.
In the era of fast growing newer technologies, and in computer and internet friendly environment the manuscripts preparation, submission, review, revision, etc and all can be done and checked with a click from all corer of the world, at any time. Of course there is always a scope for improvement in every field and none is perfect. To progress, one needs to identify the areas of one's weakness and to strengthen them.
It is well said that "happy beginning is half done" and it fits perfectly with JCDR. It has grown considerably and I feel it has already grown up from its infancy to adolescence, achieving the status of standard online e-journal form Indian continent since its inception in Feb 2007. This had been made possible due to the efforts and the hard work put in it. The way the JCDR is improving with every new volume, with good quality original manuscripts, makes it a quality journal for readers. I must thank and congratulate Dr Hemant Jain, Editor-in-Chief JCDR and his team for their sincere efforts, dedication, and determination for making JCDR a fast growing journal.
Every one of us: authors, reviewers, editors, and publisher are responsible for enhancing the stature of the journal. I wish for a great success for JCDR."



Thanking you
With sincere regards
Dr. Rajendra Kumar Ghritlaharey, M.S., M. Ch., FAIS
Associate Professor,
Department of Paediatric Surgery, Gandhi Medical College & Associated
Kamla Nehru & Hamidia Hospitals Bhopal, Madhya Pradesh 462 001 (India)
E-mail: drrajendrak1@rediffmail.com
On May 11,2011




Dr. Shankar P.R.

"On looking back through my Gmail archives after being requested by the journal to write a short editorial about my experiences of publishing with the Journal of Clinical and Diagnostic Research (JCDR), I came across an e-mail from Dr. Hemant Jain, Editor, in March 2007, which introduced the new electronic journal. The main features of the journal which were outlined in the e-mail were extensive author support, cash rewards, the peer review process, and other salient features of the journal.
Over a span of over four years, we (I and my colleagues) have published around 25 articles in the journal. In this editorial, I plan to briefly discuss my experiences of publishing with JCDR and the strengths of the journal and to finally address the areas for improvement.
My experiences of publishing with JCDR: Overall, my experiences of publishing withJCDR have been positive. The best point about the journal is that it responds to queries from the author. This may seem to be simple and not too much to ask for, but unfortunately, many journals in the subcontinent and from many developing countries do not respond or they respond with a long delay to the queries from the authors 1. The reasons could be many, including lack of optimal secretarial and other support. Another problem with many journals is the slowness of the review process. Editorial processing and peer review can take anywhere between a year to two years with some journals. Also, some journals do not keep the contributors informed about the progress of the review process. Due to the long review process, the articles can lose their relevance and topicality. A major benefit with JCDR is the timeliness and promptness of its response. In Dr Jain's e-mail which was sent to me in 2007, before the introduction of the Pre-publishing system, he had stated that he had received my submission and that he would get back to me within seven days and he did!
Most of the manuscripts are published within 3 to 4 months of their submission if they are found to be suitable after the review process. JCDR is published bimonthly and the accepted articles were usually published in the next issue. Recently, due to the increased volume of the submissions, the review process has become slower and it ?? Section can take from 4 to 6 months for the articles to be reviewed. The journal has an extensive author support system and it has recently introduced a paid expedited review process. The journal also mentions the average time for processing the manuscript under different submission systems - regular submission and expedited review.
Strengths of the journal: The journal has an online first facility in which the accepted manuscripts may be published on the website before being included in a regular issue of the journal. This cuts down the time between their acceptance and the publication. The journal is indexed in many databases, though not in PubMed. The editorial board should now take steps to index the journal in PubMed. The journal has a system of notifying readers through e-mail when a new issue is released. Also, the articles are available in both the HTML and the PDF formats. I especially like the new and colorful page format of the journal. Also, the access statistics of the articles are available. The prepublication and the manuscript tracking system are also helpful for the authors.
Areas for improvement: In certain cases, I felt that the peer review process of the manuscripts was not up to international standards and that it should be strengthened. Also, the number of manuscripts in an issue is high and it may be difficult for readers to go through all of them. The journal can consider tightening of the peer review process and increasing the quality standards for the acceptance of the manuscripts. I faced occasional problems with the online manuscript submission (Pre-publishing) system, which have to be addressed.
Overall, the publishing process with JCDR has been smooth, quick and relatively hassle free and I can recommend other authors to consider the journal as an outlet for their work."



Dr. P. Ravi Shankar
KIST Medical College, P.O. Box 14142, Kathmandu, Nepal.
E-mail: ravi.dr.shankar@gmail.com
On April 2011
Anuradha

Dear team JCDR, I would like to thank you for the very professional and polite service provided by everyone at JCDR. While i have been in the field of writing and editing for sometime, this has been my first attempt in publishing a scientific paper.Thank you for hand-holding me through the process.


Dr. Anuradha
E-mail: anuradha2nittur@gmail.com
On Jan 2020

Important Notice

Original article / research
Year : 2021 | Month : August | Volume : 15 | Issue : 8 | Page : NC06 - NC10 Full Version

Comparison of Central Corneal Thickness and Endothelial Cell Density in Patients with Various Types of Glaucoma and Patients without Glaucoma: A Case-control Study


Published: August 1, 2021 | DOI: https://doi.org/10.7860/JCDR/2021/48907.15227
Khushboo Chawla, Shailesh Gadaginamath, Ashish Kumar Shah

1. Senior Resident, Department of Ophthalmology, Shekar Eye Hospital, Bengaluru, Karnataka, India. 2. Senior Consultant, Department of Ophthalmology, Shekar Eye Hospital, Bengaluru, Karnataka, India. 3. Senior Resident, Department of Psychiatry, Datta Megha Institute of Medical Sciences, Wardha, Maharashtra, India.

Correspondence Address :
Dr. Khushboo Chawla,
2E/20, Jhandewalan Extension, New Delhi-110055, India.
E-mail: khushboo.3dec@gmail.com

Abstract

Introduction: Corneal affection in glaucoma patients is very high due to various risk factors that may lead to unforeseen and unplanned deleterious effects on the cornea leading to vision loss. Accurate intraocular pressure determination requires corneal thickness measurement and uncontrolled intraocular pressures, use of long term medication, intra ocular surgeries including cataract and glaucoma shunt surgeries may cause significant endothelial loss. Therefore, adequate planning and management and follow-up in these patients is required weighing all the long term consequences and emphasis the need for implementing adequate precautions.

Aim: To evaluate and compare the Central Corneal Thickness (CCT) and corneal Endothelial Cell Density (ECD) in patients with glaucoma and without glaucoma by specular microscopy.

Materials and Methods: A case-control study conducted in a Shekar Eye Hospital, Bengaluru, Karnataka, India, was conducted from August 2016 till April 2018 on a total 182 eyes from 182 patients were evaluated comprising of 91 cases and 91 controls. All participants underwent a detailed ophthalmological examination including slit lamp biomicroscopy, Intraocular Pressure (IOP) measurement, and CCT and ECD measurement by Tomey EM 3000 noncontact specular microscopy. The Statistical analysis was completes using Statistical Package For the Social Sciences (SPSS) 18.0 and R environment version 3.2.2 software’s.

Results: The CCT of the glaucoma patients and the controls showed no significant difference (p-value=0.172). The CCT was comparatively thicker in Ocular Hypertension (OHTN) patients and thinner in Normal Tension Glaucoma (NTG) however statistical significance was not established. The mean ECD of controls was 2509.05±298.48 (cells/mm3) and that of cases was 2465.68±392.91 (cells/mm3) (p-value=0.404). The difference in the ECD amongst the glaucoma subgroups was not statistically significant (p-value=0.588). However, a lower ECD were seen in Pseudoexfoliation Glaucoma (PXG) and Primary Angle Closure Glaucoma (PACG) subgroups.

Conclusion: No significant difference was found in CCT and endothelial cell in cornea of patients with and without glaucoma. Normal Tension Glaucoma (NTG) patients have comparatively thinner corneas and OHTN patients had thicker corneas. There was no significant correlation established between ECD of Normal corneal vs. Glaucoma and its subgroups.

Keywords

Normal tension glaucoma, Ocular hypertension, Primary open angle glaucoma, Specular microscopy

Worldwide glaucoma is one of the major causes of irreversible blindness affecting almost 63.4 million people worldwide (1) with Primary Open Angle Glaucoma (POAG) being the most common type. Early diagnosis and treatment of glaucoma becomes a major issue in order to decrease the prevalence of the blindness caused from glaucoma.

The Ocular Hypertension (OHTN) study and European glaucoma prevention study emphasised on the importance of cornea being the most predictable factor for glaucoma progression (2),(3). OHTN may progress to POAG if not diagnosed and managed on time. It is worth noting, that the early manifest glaucoma trial, Intraocular Pressure (IOP) and thus Central Corneal Thickness (CCT) was not the criteria for nothing its progression and its management (2). However, the treating ophthalmologist remains in a dilemma at times regarding the contributory factors to be considered. Tonometry is the primary approach which is influenced by the mechanical and the morphological properties of the cornea, CCT being of paramount importance (2). Study by Micheallester have shown variations in corneal thickness change the resistance of the cornea to indentation during IOP measurement (2),(4). It is attributed to the fact that various formulas used take into consideration the CCT and the curvature, but the biomechanics of the cornea play an important role (2),(5). Thus, this may affect the accuracy of the measurement of IOP. A thinner cornea may require less force to applanate it, leading to underestimation of the true IOP, while a thicker cornea would need more force thus giving an artifactually high IOP reading (6). Corneal endothelial cells is a layer of hexagonal cells that play an important role in maintaining corneal clarity by actively dehydrating the corneal stroma and thereby allowing an orderly lattice of collagen fibrils to create a transparent tissue. Corneal endothelial cells do not regenerate but instead enlarge to maintain corneal clarity (7). Many factors affect the corneal endothelium in glaucoma patients, including direct damage due to elevated IOP, altered trabecular meshwork in congenital cases and associated corneal structural changes, ocular surgery, and ocular trauma (8). These may lead to a reduced corneal Endothelial Cell Density (ECD) in glaucoma patients (9).

The IOP is the only modifiable risk factor known for glaucoma thus should be recorded accurately. Misdiagnosis of new patients as POAG instead of Normal Tension Glaucoma (NTG) or normal, and normal being labelled as OHTN is attributed to imprecise measurement of IOP in the clinics. The follow-up of these patients is altered at times due to fallacious IOP recorded without considering the CCT also the line of management may differ based on the baseline and the target IOP set (10).

This study was conducted to evaluate the corneal morphology in glaucoma patients recently diagnosed or who are undergoing multiple medical and surgical treatments in order to control the progression of disease. Misdiagnosis, unforeseen and unplanned deleterious effects on the cornea to the enumerated reasons may lead to vision loss. In addition, uncontrolled IOP, use of long term medication, intra ocular surgeries including cataract and glaucoma shunt surgeries may cause significant endothelial loss.

Material and Methods

A case-control study was conducted in Shekar Eye Hospital, Bangalore, Karnataka, India, for duration of 21 months from August 2016 till April 2018. The study was approved by the the Hospital Ethical Committee (Ref no: SEH/IEC/2016-18/32) and adhered to tenets of Helsinki Declaration.

Corneal morphology of total 182 eyes from 182 patients were evaluated comprising of 91 cases and 91 controls between the age group of 40-80 years. Right eye was considered for uniformity and only phakic patients were included.

Inclusion and exclusion criteria: Patients presenting to the Out Patient Department (OPD) for a routine/follow-up visit who were newly diagnosed as well as cases of proven glaucoma of different duration and types were included in study. Healthy individual with no ocular pathology, presenting for routine evaluation were taken as controls. Patients with active ocular infection, contact lens users, corneal conditions (Keratoconus, Fuchs dystrophy, corneal degeneration and dystrophies, chemical injury), and congenital diseases affecting cornea, history of previous retinal lasers and history of ocular trauma were excluded.

After considering inclusion and exclusion criteria CCT and ECD of patients with glaucoma were compared with the healthy subjects and between the different glaucoma subtypes namely POAG, Primary Angle Closure Glaucoma (PACG), Pseudoexfoliative Glaucoma (PXG), NTG, OHTN.

Study Procedure

After taking an informed consent, demographic details of the patients were collected. All patients were interviewed regarding diagnosis and duration of glaucoma, detailed ocular medication history. A comprehensive ophthalmic examination of anterior segment
examination by slit lamp biomicroscopy and detailed fundus examination was done to establish a diagnosis of the type of glaucoma and any associated ocular pathology. The IOP was measured by well calibrated Goldmann Applanation tonometry, the average of two readings was taken as the final IOP and documented to monitor the treatment and planning of further management. Gonioscopy was done with Goldmann three-mirror Gonioscope to assess the angle. The glaucoma patients were then further categorised into five subgroups. Specular microscopy (by Tomey EM 3000 Specular microscope) was done for all the cases and controls and analysed.

Statistical Analysis

Descriptive and inferential statistical analysis has been carried out in the present study. Results on continuous measurements are presented on Mean±SD (min-max) and results on categorical measurements are presented in number (%). Significance is assessed at 5% level of significance. Analysis of variance (ANOVA), Student t-test (two tailed, independent), Chi-square/Fisher’s exact test has been used to find the significance of study parameters. The Statistical analysis was completes using Statistical Package For the Social Sciences (SPSS), and R environment version 3.2.2 software’s.

Results

The mean age of patients in glaucoma group was 62.31±9.02 years and in control group 63.26±9.01 years (p=0.475, ANOVA test). The cases were subdivided into five subgroups based on the type of glaucoma diagnosed namely POAG, NTG, PACG, PXG and OHTN (Table/Fig 1).

Among cases, 26.4% (n=24) did not have any medical history. The IOP of most patients was within normal limits i.e., <20 mmHg (Table/Fig 2). Specular microscopy was conducted and the CCT and ECD (number of endothelial cell per square millimeter) (11) values were taken into consideration. The mean CCT of cases was 513.41±38.51 μm and that of controls group was 520.71±33.15 μm. The mean ECD of the cases was 2465.68±392.91 (cells/mm3) and control was 2509.05±298.48 (cells/mm3). Both the parameters showed no statistically significant difference among the two groups (p-value=0.172 and p-value=0.404, respectively) (Table/Fig 3).

The CCT was measured between the subgroups of Glaucoma patients and was compared within the five subgroups and with controls using ANOVA Test. The comparison between these tests revealed the maximum corneal thickness (531±23.88 μm) was present in OHTN group and the thinnest (499.68±35.83 μm) observed in NTG subgroup (p-value=0.053) (Table/Fig 4).

The ECD was also measured by specular microscopy and comparison between the controls and the glaucoma subtypes, also within the glaucoma subgroups was done. The mean ECD was maximum in POAG and Ocular HTN types (2517.87±245.30 cells/mm3) and 2559.75±268.21 (cells/mm3) respectively) and was minimum in PACG group (2378.17±677.94 cells/mm3) followed by PXG. However, this comparison between these groups done using ANOVA test did not show statistically significant result (p-value=0.588) (Table/Fig 4).

(Table/Fig 4) shows the mean CCT and mean ECD of the cases with respect to the duration of disease. The comparison showed a significant association with the duration of disease with p-value=0.098. It was observed that patients with more than five year duration of disease had the thinnest average CCT which could have been a contribution of long term IOP fluctuations and increased IOP for a longer duration of disease. But comparatively thicker corneas were seen among patients with less than two years (Table/Fig 5). The Mean ECD comparison between cases of different duration of prevalence of disease showed no statistical difference among cases with glaucoma of different durations (p-value=0.521).

Many studies in the past few decades have proven myopia as one of the most common risk factor of glaucoma. In our study, the spherical equivalent of 64.8% cases was low hyperopia i.e., between 0 and +3D followed by 22% patients having low myopia (i.e., 0 to -3D). The type of refractive error may vary with type of glaucoma such as hyperopia being common among ACG and myopia amongst POAG groups. In the present study, there was only one high hyperopia (i.e., > +6) but was a known case of POAG.

Discussion

Glaucoma is a chronic optic neuropathy, with newer advances there are evidences of associated corneal morphological changes in longstanding glaucomatous eyes. CCT is the most common risk factor in predicting the progression of glaucoma which is the static property of cornea. Eyes with thin corneas have an underestimation of IOP, and eyes with thick corneas have an overestimation of IOP (12).

Hypothesis by Gagnon M et al., states constant high IOP results in compression damage on the endothelial cells, long term use of ocular hypotensive drugs with added preservatives have deleterious effect on the cornea (13). In addition to these glaucoma surgeries with antifibrotic use may have toxic effect on the cornea.

This study included 182 eyes of cases and controls comparing them for CCT and ECD changes. Comparison made between cases controls but also among subgroups of cases (glaucoma) namely, POAG, PACG, PXG, NTG and ocular HTN. The data showed no significant difference in the CCT and ECD among age matched cases and controls (p-value=0.172 and p-value=0.475). However, aging may influence our results with respect to the endothelial cell count as advancing age is related to progressive decline in ECD (14),(15).

The subgroup analysis, done among glaucoma cases for CCT, showed OHTN patients had a comparatively higher CCT and patients with NTG had the least CCT (p=0.153) amongst all, which was found to be in accordance with the study conducted by R. Thomas in Vellore on NTG and OHTN patients. They found thicker CCT in OHTN patients which lead to overestimation of IOP thus recommended use of correction factor for actual IOP determination (6). Similar results were found by Morad Y who found a significantly lower CCT in NTG patients when compared to OAG and normal patients thus underestimation of IOP and misdiagnosis was a major factor brought into light (16). While Herndon LW et al., on comparison of CCT of OAG and normal individuals showed thicker corneas in OAG patients (17). Lee J et al., concluded no significant difference between CCT of NTG and OAG (18).

Gagnon MM et al., and other studies conducted in other parts of Europe found that corneal endothelial cell counts were significantly lower in patients with glaucoma than in controls (p-value <0.0001) (13),(19). Whereas, Cho S et al., showed low ECD in POAG group as compared to NTG group in his study (9). A research by Tomaszewski B et al., reflected that psudoexfoliation have a lower ECD irrespective of glaucoma development (20). Another study by Stroligo MN et al., echoed the same result of lower central ECD in patients with PXG as compared to POAG and PACG. He also concluded a lower ECD in patients with glaucomatous eyes as compared to non-glaucomatous eyes (19).

In the present study, it was found comparable ECD between the cases and controls (p=0.404). Within the subgroups of glaucoma PACG and PXG group had the least ECD of 2378.17±677.94 cells/mm2 and 2392.17±258.37 cells/mm2 respectively compared to the POAG and OHTN, but was not clinically significant (p=0.550).

Cho H and Kee C conducted a study and found a positive relation between myopia, increased axial length as a risk factor for glaucoma in Asian population thus explaining the increased prevalence of disease among Asians than amongst White (21). Also, Marcus M et al., stated in their study that risk of glaucoma development and progression increases with the degree of myopia (22). In contrast this study, there was no such relationship between refractive status and glaucoma.

Various systemic illnesses are related to progression of glaucoma. The correlation between Diabetes and Glaucoma however being the most researched is still under debate. Other medical illness such as HTN, migraine asthma, usage of steroid medication in form of inhalers, have been analysed in our study highlighting no correlation to changes observed in the corneal morphology. HTN was common accounting for 47.2% of all medical conditions. One patient with NTG had a known history of migraine and two patients with NTG complained of significant history of hypotension episodes, which could have been considered due to the similar vascular aetiology of vasoconstriction and inadequate dilatation of microcirculation. Study by Cursiefen C et al., highlighted individuals with migraine may develop NTG rather than high tension glaucoma (23). The Tamiji study conducted in by Suzuki Y et., showed that HTN and POAG were age related morbidities coinciding with this study population (24).

The duration and constant high IOP and fluctuations are other factors found to have deleterious effects on CCT and the ECD. It was observed in this study that patients with IOP >20 mmHg the mean CCT and mean ECD were comparable to the control groups. The overestimation of actual IOP due to high corneal thickness and vice versa should be dealt in mind while doing the clinical work up of a patient. However, low CCT is a risk factor itself, independent of IOP but has not been determined completely (25). The other contributory factors such as thicker corneas overestimating the IOP, duration of high IOP and previous use of Anti-Glaucoma Medication (AGM) come into role while determining the corneal health.

This study showed majority of patients having glaucoma diagnosed since 2-5 years. Out of the total 91 patients, 14 were recently diagnosed including those diagnosed in our hospital OPD on presentation for a routine check up. The CCT of patients with a progressive decline with duration of disease when comparing more than two years with more than five years duration, reached the least value amongst those with more than five years of glaucoma (p-value=0.098). However, other contributory factors such as decline in CCT with age have been inconsistent. Many studies did not find a significant difference in mean CCT with increasing age and agreed with our cross-sectional study (26). On the other hand Barbados eye study showed an association between thinner corneas and age (27). The ECD did not have any significant difference when compared based on the duration of disease.

The cornea can be defined by its physical dimensions, such as its thickness, or physical behaviour, for example, the biochemical behaviour of cornea also known as corneal hysteresis. Recent studies have shown that corneal hysteresis also provides valuable information regarding presence of glaucoma, risk of progression and management. Corneal hysteresis measurement has been made possible by the Reichert Ocular Response Analyzer (ORA) (5).

Limitation(s)

As corneal endothelium is a dynamic structure, the need was considered to follow-up the patients in the course of time for corneal morphology by specular microscopy. A serial monitoring would give a more insight into the prospective changes occurring as a result of the disease process, ageing and treatment. Also, considering the subgroups like PXG and PACG, a comparison with the PPXF without glaucoma and PAC/PAC suspects respectively will provide better understanding of the pathology occurring and thus, preventive measures can be taken while planning of management.

Conclusion

No significant difference was found in Central Corneal Thickness (CCT) and Endothelial Cell Density (ECD) of glaucoma vs. healthy patients’ cornea. NTG patients have comparatively thinner corneas and OHTN patients had thicker corneas. Thus, IOP should be corrected based on the corneal thickness to avoid any over or underestimation. The endothelial density was noted to be lower in angle closure glaucoma and pseudoexfoliation glaucoma subgroup, although the results were comparable with POAG and healthy controls. Formation of correct diagnosis of the type of glaucoma is essential as PXG and PACG may have endothelial compromise. With advancement in medical and surgical management, evaluation of cornea becomes an important factor during diagnosis, treatment and follow-up of glaucoma. Thus, for long term safety a detailed corneal examination including CCT and ECD is an essential step in the workup and follow-up of a glaucoma patient for comprehensive management and better outcome.

Acknowledgement

We acknowledge the staff of the investigation lab and patients in Department of Ophthalmology of the institute for the co-operation and participation in the study. We also acknowledge Dr. Rajashekar Y.L., Managing Director and Head of Department Ophthalmology for his expert assistance throughout the process of this study.

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DOI and Others

10.7860/JCDR/2021/48907.15227

Date of Submission: Feb 08, 2021
Date of Peer Review: Mar 25, 2021
Date of Acceptance: May 29, 2021
Date of Publishing: Aug 01, 2021

AUTHOR DECLARATION:
• Financial or Other Competing Interests: None
• Was Ethics Committee Approval obtained for this study? Yes
• Was informed consent obtained from the subjects involved in the study? Yes
• For any images presented appropriate consent has been obtained from the subjects. NA

PLAGIARISM CHECKING METHODS:
• Plagiarism X-checker: Feb 09, 2021
• Manual Googling: May 20, 2021
• iThenticate Software: Jul 01, 2021 (16%)

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