Abstract

Research Article

A study to correlate the central corneal thickness to the severity of diabetic retinopathy and HbA1c levels in type 2 diabetes mellitus

Neha Nargis*, Seema Channabasappa, Nischala Balakrishna and Singri Niharika

Published: 14 December, 2021 | Volume 5 - Issue 2 | Pages: 029-038

Background: Diabetic retinopathy (DR) is one of the most common causes of preventable blindness. Patients with Diabetes Mellitus (DM) develop not only DR but also corneal endothelial damage leading to anatomical and physiological changes in cornea. Central corneal thickness (CCT) is a key parameter of refractive surgery and Intraocular pressure (IOP) estimation. The role of CCT and higher glycemic index in DR needs to be researched upon.
Objectives: To identify the corneal endothelial morphology in patients with type 2 DM, to measure the Central Corneal thickness (CCT) in patients with type 2 Diabetes Mellitus, to assess the relationship of CCT with HbA1C levels in the study group and to correlate the CCT with the severity of Diabetic retinopathy in the study group.
Methods: A cross-sectional observational study was conducted between January 2018 and June 2019 in Vydehi Institute of Medical Sciences and Research Centre, Bangalore. The study included 100 subjects with type 2 DM for 5 years or more. Patients with comorbidities that may affect the severity of DR or alter CCT and other corneal endothelial parameters such as glaucoma, previous ocular surgery or trauma, corneal degenerations and dystrophies, chronic kidney disease and Hypertension were excluded. DR was assessed by dilated fundoscopy, fundus photography and optical coherence imaging of the macula and graded as per the Early Treatment of Diabetic Retinopathy Study (ETDRS) classification. CCT and other corneal endothelial parameters were measured through specular microscopy. Relevant blood investigations including blood sugar levels were done for all patients.
Statistical analysis: Relationship between CCT and grades of DR and HbA1c levels were established using the Chi-Square test. The level of significance was set at p < 0.05.
Results: The mean CCT in patients with no diabetic retinopathy, very mild and mild non-proliferative diabetic retinopathy (NPDR), moderate NPDR, severe and very severe NPDR and PDR was 526.62 ± 8.084 μm, 542.07 ± 8.713 μm, 562.16 ± 8.255 μm, 582.79 ± 7.368 μm and 610.43 ± 18.256 μm respectively. Analysis of the relationship between CCT and severity of DR showed a statistically significant positive correlation between the two parameters (Pearson r = 0.933, p = 0.001). Beyond this, a correlation was found between all the corneal endothelial parameters and severity of DR. Multivariate analysis showed that advanced DR was positively correlated with CV (r  = 0.917) and CCT (r = 0.933); while it was negatively correlated with ECD (r = -0.872) and Hex (r = -0.811). 
A statistically significant correlation was also found between CCT and HbA1c. Also increasing age, duration of DM and higher glycemic index were positively correlated with severity of DR. 
Conclusion: This study, by demonstrating a strong correlation between the central corneal thickness to the severity of DR and HbA1c levels emphasizes the importance of evaluation of corneal endothelial morphology in the early screening and diagnosis of microvascular complications of DM.

Read Full Article HTML DOI: 10.29328/journal.ijceo.1001041 Cite this Article Read Full Article PDF

Keywords:

Diabetic retinopathy; Central corneal thickness; HbA1c; Corneal endothelial morphology; Diabetes mellitus

References

  1. International Diabetes Federation Atlas, International Diabetes federation. http://www.idf.org/diabetesatlas. Seventh edition. 2015
  2. Shukla EJ, Nicholson AD, Agrawal AH, Rathod DB. Correlation between severity of Type 2 diabetes mellitus and corneal morphology using specular microscopy in Indian population: A case-control study. Sudanese J Ophthalmol. 2016; 8: 30-35.
  3. Schultz RO, Matsuda M, Yee RW, Edelhauser HF, Schultz KJ. Corneal endothelial changes in type I and type II diabetes mellitus. Am J Ophthalmol.1984; 98: 401-410. PubMed: https://pubmed.ncbi.nlm.nih.gov/6486211/
  4. Rangnath KN, Parekh R, Suresh KP, Dharmalingam M. Corneal endothelium count and thickness in diabetes mellitus. Int J Diab Dev Ctries. 2006; 26: 24-25.
  5. Choo MM, Prakash K, Samsudin A, Soong T, Ramli N, et al. Corneal changes in T2DM in Malaysia. Int J Ophthalmol. 2010; 3: 234-236. PubMed: https://pubmed.ncbi.nlm.nih.gov/22553561/
  6. El-Agamy A, Alsubaie S. Corneal endothelium and central corneal thickness changes in T2DM. Clin Ophthalmol. 2017; 11: 481-486. PubMed: https://pubmed.ncbi.nlm.nih.gov/28280298/
  7. Ahuja SS, Bammigatti C, Kumar P. Corneal Endothelial changes in patients of Type 2 DM using specular Microscopy. EC Ophthalmol. 2017; 6: 100-107.
  8. Abdulghani YS, Ali TO. Correlation between central corneal thickness and diabetes in Sudanese patients. National J Med Res. 2013; 3: 309-311.
  9. Sasmal NK, Das S, Singh S. Association of central corneal thickness and central corneal endothelial cell count with progressive stages of diabetic retinopathy. J Evid Based Med. Healthc. 2017; 4: 4924-4928.
  10. Dabas R, Sethi S, Garg M, Aggarwal R, Lamba S, et al. Central Corneal Thickness (CCT) in Diabetic Subjects and its Correlation with Disease Duration and Severity. Ann Int Med Den Res. 2017; 3: OT04-OT06.
  11. Kaur P, Singh B, Bal BS, Kaur I. CCT in T2DM patients and its correlation with duration, HbA1c levels and severity of retinopathy. IOSR J Dental Med Sci. 2016; 15: 91-94.
  12. American diabetes association “Tests of glycemia in diabetes”, Clinical practice recommendations. 2003. 107-108.
  13. Kadhim YJ, Farhood QK. Central corneal thickness of Iraqi population in relation to age, gender, refractive errors, and corneal curvature: a hospital-based cross-sectional study. Clin Ophthalmol. 2016; 10: 2369–2376. PubMed: https://pubmed.ncbi.nlm.nih.gov/27932859/
  14. Busted N, Olsen T, Schmitz O. Clinical observations on the corneal thickness and the corneal endothelium in DM. Br J Ophthalmol. 1981; 65: 687-690. PubMed: https://pubmed.ncbi.nlm.nih.gov/7317320/
  15. Bowling B. Kanski's clinical Ophthalmology. 8 ed: Elsevier; 2016.
  16. Kumari R, Saha BC. Central corneal thickness and diabetes – a study of correlation in terms of duration and glycemic control. Int J Contempor Med Res. 2017; 4: 767-769.
  17. Inoue K, Kato S, Inoue Y, Amano S, Oshika T. The corneal endothelium and thickness in type II diabetes mellitus. Jpn J Ophthalmol. 2002; 46: 65-69. PubMed: https://pubmed.ncbi.nlm.nih.gov/11853716/
  18. Storr‐Paulsen A, Singh A, Jeppesen H, Norregaard JC, Thulesen J. Corneal endothelial morphology and central thickness in patients with type II diabetes mellitus. Acta Ophthalmol. 2014; 92: 158-160. PubMed: PubMed: https://pubmed.ncbi.nlm.nih.gov/23387877/

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