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Asian Diabetic Corneas: A Study in Astigmatism

Abstract

Purpose: Diabetic corneas have ultrastructural changes that can lead to dry eye, abnormal healing after trauma. The literature is sparse on the topic of Asian diabetics corneas with good Va and automated refractive keratometry readings. At our retina clinic in California, we retrospectively evaluated the keratometry readings of corneas of Diabetic patients in an Asian population. Are there external refractive or superficial keratometry differences in Asian Diabetic vs Asian Control eyes?

Methods: Corneal topography was performed using Topcon KR-8000PA Auto Kerato- Refractometer (Oakland, NJ) on patients as part of the refractive screening prior to dilation for evaluation of diabetic retinopathy.
image-Asian-Diabetic-Corneas-A-Study-in-Astigmatism

Inclusion criteria: Va = 20/15 to 20/50. Recent HbA1c/FBS within 6 months of exam; Controls were patients without diabetes (nl FBS). Exclusion criteria: corneal scarring, LASIK, corneal surgery or previous macula laser.

Results: Total of 38 pts: 17 DM, 21 C; 17M, 21F; Age 43-90yrs; Avg 65.6yrs±10.8

Asians 22 pts: 11M, 11F; Age: 43-90yrs; Avg 61.4yrs±10.5,
– 9 DM – HbA1c: Range 6.1-7.7%, Avg 6.9%±0.61; FBS: Range 95-197mg/dL; Avg 136mg/dL±35
– 13 C – HbA1c: Range 5.5-6.0%, Avg 5.8%±0.18; FBS: Range 84-119mg/dL; Avg 99mg/dL±10

Non-Whites 27 pts: 12M,15F; Age: 43-90yrs; Avg 64.4yrs ±11.2
– 13 DM – HbA1c: Range 6-7.7%; Avg 6.73%±0.62; FBS: Range 87-197mg/dL; Avg
124.92mg/dL±33.07
– 14 C – HbA1c: Range 5.5-6.0%; Avg 5.84%±0.18; FBS: Range 84-119mg/dL; Avg
98.08mg/dL±10.39

For OS: Asian diabetics (ADM) have a median horizontal axis (HA) of 158° vs. Asians controls (AC) median 28° (p=0.02). Non-White diabetics (NWDM) have a median horizontal axis of 158° vs. Non-White controls (NWC) 28.5° (p=0.05).
image2-Asian-Diabetic-Corneas-A-Study-in-Astigmatism

Conclusions: Abnormal collagen fibrils are noted within the cornea by ultra-structural exam in diabetic patients. The irregular astigmatism occurring in diabetic patients may be due to the abnormal collagen which may play a role in decreased vision for diabetics. Asian DM eyes have an astigmatic axis closer to 150° whereas Asian Control eyes have an astigmatic axis closer to 50°. This has implications for refractive and cataract surgery.

Background

Diabetic corneas are known to have abnormal collagen fibrils.1,2,3,4 Asian corneas have not been well studied with respect to other ethnic minority corneas.

Purpose

To assess the differences in diabetic and non-diabetic corneas, specifically in Asian and non-White populations.

Methods

Corneal topography was performed using Topcon KR- 8000PA Auto Kerato-Refractometer (Oakland, NJ) on patients as part of the refractive screening prior to dilation for evaluation of diabetic retinopathy.

Inclusion Criteria
● Va = 20/20 – 20/50
● No keratoconus
● Controls: normal volunteers or patients with no history
of corneal disease or diabetes
● Diabetics: HbA1c > 6.0 within 3 months of corneal
topography exam or previous diagnosis by PCP or endocrinologist.

Results

38 patients met the inclusion criteria: ● 11 Non-White Controls (NWC)
2 Male/9 Female. Avg Age: 61.7 + 11.8 yrs
(Range 43 – 81 yrs)
● 12 Non-White Diabetics (NWD)
9 Male/ 5 Female. Avg Age: 69.1 + 9.7 yrs
(Range 55 – 90 yrs) ● 14 Asian Controls (AC)
4 Male/ 10 Female. Avg Age: 62.8+11.4 yrs
(Range 43 – 81 yrs) ● 10 Asian Diabetics (AD)
8 Male/ 2 Female. Avg Age: 69.9 + 9.7 yrs (Range 56 – 90 yrs)

Conclusion

1. This small study suggests that East Asian diabetic corneas are different from non-White diabetic corneas with respect to astigmatism.
2. This may have implications for cataract surgery and refractive surgery considerations.
3. We hope future studies will further investigate the corneas of Asian diabetic patients.

References

1. Sady C, Khosrof S, Nagarai R. Advanced Maillard Reaction and cross linking of corneal collagen in diabetes. Biochem Biophys Res Commun. 1995; 214: 793-797.
2. Paudel RP, Adhikari BN, Kaini KR. Clinical evaluation of corneal astigmatism in non-diabetic and diabetic patients. Nepal Med Coll J. 2006; 8: 162-165.
3. Kaji Y, Usui T, Oshika T et al. Advanced glycation end products in diabetic corneas. Invest Ophthalmol Vis Sci. 2000; 41:362-368.
4. Sato N, Nakamura M, Chikama T et al. Abnormal deposition of Laminin and Type IV collagen at corneal epithelium basement membrane during wound healing in diabetic rats. Jpn J Ophthalmol. 1999; 43:343-347.

Authors: Gloria Wu, VIdhya Gunasekaran and Victor Chen
For correspondence, email gloria_wumd@sbcglobal.net

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