Al

Participants: One hundred patients with NIDDM evenly divided between those with less than 5 years of diabetes (group 1) and those with diabetes of more than 10 years of duration (group 2) were included in the study. Normal subjects without diabetes or any other ocular and systemic pathology age and gender matched to the NIDDM patients served as controls for the two diabetic groups. One eye of each patient and control was chosen for the study.

Methodology: Topcon Specular microscope (Topcon SP 2000P) was used to measure the corneal thickness in both cases and control groups.

Results: Mean corneal thickness of patients with less than 5 yrs of diabetes was 0.5162±0.0367mm and control group was 0.5136±0.0306 mm with no significant difference in two groups. (p= 0.65). However, mean corneal thickness of patients of group 2 was 0.5212±0.0306 mm and control group was 0.49957±0.0330 mm with significant difference in both groups. (p= 0.001)

Conclusion: The study suggests abnormal function of corneal endothelium in diabetes and warrants for minimal invasive procedures for surgery and prompt treatment of other compounding endothelial insults in diabetic patients. Al-Shifa Journal of Ophthalmology 2005; 1: 42-44 © Al-Shifa Trust Eye Hospital, Rawalpindi, Pakistan

The most important function of the endothelium is to prevent stromal swelling and maintain its water content at about 78% through its barrier and pump functions. A corneal pachymeter measures corneal thickness, which is a sensitive indicator of endothelial physiology that correlates well with functional measurements such as aqueous fluorophotometry.

Originally received: August 10, 2004
Accepted: November 15, 2004
Correspondence to Mustafa Abdul Hameed Ismail, Department of Cornea and anterior segment, Al-Shifa Trust Eye Hospital, Rawalpindi, Pakistan.

The value of optical corneal pachymetry is manifolds. It provides information about the normal physiological hydration dynamics of cornea. Since corneal thickness is directly related to the health of corneal endothelium, its measurement is an excellent indication of the amount of endothelial trauma especially after surgery¹.

Diabetes is a chronic debilitating disease of insulin deficiency or resistance. Once thought to be a disease of affluent societies, diabetes is on the rise in countries like Pakistan because of changing socio-economics and life styles. The westernization of the society has resulted in increase in the number of patients presenting with complications of diabetes to our hospitals.

Purpose

To evaluate the effect of non-insulin dependent diabetes on the central corneal thickness and compare it with that of normal individuals

Design of Study

The study was a hospital based case control study using Topcon SP 2000 specular microscope.

Participants

Patients with NIDDM who came to the Al-Shifa Trust Eye Hospital, Rawalpindi, for their care were screened for eligibility for the study. One hundred patients with NIDDM evenly divided between those with less than 5 years of diabetes (group 1) and those with diabetes of more than 10 years of duration (group 2) were included in the study. Normal subjects without diabetes or any other ocular and systemic pathology age and gender matched to the NIDDM patients served as controls for the two diabetic groups. One eye of each patient and control was chosen for the study.

Methodology

Topcon Specular microscope (Topcon SP-2000P) was used to measure the corneal thickness of both the cases and controls. Specular Microscope is a new instrument in the field of ophthalmic diagnostic imaging, capable of performing measurement of corneal thickness by non-contact methods. Slit light is emitted in a slanting manner for the patient’s cornea and the light sensor brings in the light reflected by the front and backsides of the cornea. The corneal thickness is calculated by using the interval between the front reflection image and backside reflection image on the light sensor. This is the optical focusing method of pachymetry.

Results

Mean corneal thickness of patients with less than 5 yrs of diabetes was 0.5162±0.0367mm and control group was 0.5136±0.0306 mm with no significant difference in two groups. (p= 0.65)

However, mean corneal thickness of patients of group 2 was 0.5212±0.0306 mm and control group was 0.49957±0.0330 mm with significant difference in both groups. (p= 0.001)

Discussion

Measurement of corneal thickness by corneal pachymetry provides information about the normal physiological hydration dynamics of cornea. Since corneal thickness is directly related to the health of corneal endothelium, its measurement is an excellent indication of the amount of endothelial trauma. The corneas of patients with NIDDM exhibit abnormalities in corneal thickness. These changes become more pronounced with increasing disease duration. Previous studies also showed increased corneal thickness in diabetic patients^2-4, and persistent corneal edema after cataract extraction and vitrectomy, not attributable to epithelial defects suggesting abnormal function of the corneal endothelium^5-7.

Conclusion

The study suggests abnormal function of corneal endothelium in diabetes and warrants for minimal invasive procedures for surgery and prompt treatment of other compounding endothelial insults in diabetic patients.

References

1. Miller D, Dohlman CH. Effect of cataract surgery on cornea. Trans Am Acad. Ophthalmol Otolaryngol 1970; 74:369-374.

2. Olsen T, Busted N, Schmitz O. Corneal thickness in diabetes mellitus. Lancet 1980; 1:883.

3. Busted N, Olsen T, Schmitz O. Clinical observation on the corneal thickness and the corneal endothelium in diabetes mellitus. Br J Ophthalmol 1981; 65: 687-690.

4. Weston Bs, Bourne WM, Polse KA, Hodge DO. Corneal hydration control in diabetes mellitus.. Invest Ophthalmol Vis Sci 1995;36:586-595.

5. Perry HD, Foulks GN, Thoft RA. Corneal complications after closed vitrectomy through pars plana. Arch Ophthalmol 1978; 96:1401-1403.

6. Michels RD, Ryan SJ. Results and complications of 100 consecutive cases of pars plana vitrectomy. Am J Ophthalmol 1975;80:24-36.

7. Foulks GN, Thofft RA, Pery HD, Tolentino FI. Factors related to corneal endothelial complications after closed vitrectomy in diabetes. Arch Ophthalmol 1979; 97: 1076-1079.