Posters

Anthropometric, biochemical and physiological functions in patients with ocular pseudoexfoliation

Poster Details

First Author: U.Wali OMAN

Co Author(s):    N. Al Kharousi   D. Jaju           

Abstract Details

Purpose:

A major life style project named 'Hypertension in Oman: Intervention and clinical trial' was being carried out in Oman (Middle East) to assess certain anthropometric, metabolic and biochemical characteristics in a large population. The project was being executed by Department of Biochemistry and Molecular genetics of a national university. The parameters/variables being investigated included age, waist, body mass index (anthropometric), percent fat, sugar, lipid profile, leptin, insulin resistance (metabolic-biochemical), and average acetylcholine and nitroprusside response to assess endothelial cell function (physiological). With results readily available to us for all such parameters/variables, we opted to screen the same population of patients for ocular pseudoexfoliation (PEX) and categorize them into two groups; group one with ocular PEX and group 2 without ocular PEX, latter serving as a control group. Our purpose was to find any difference in above given parameters /variables between patients with ocular PEX (group 1) and patients without ocular PEX (group 2).

Setting:

This major project was carried out involving 1277 subjects recruited from five large multigenerational families in this part of the Arabian Peninsula. The setting of the clinical and laboratory facilities was carried out in a specially established, well quipped field polyclinic which comprised of an out patient clinic for slit-lamp examination, a laboratory for biochemical tests and a special unit for performing endothelial cell function. The investigations carried out in the project were marked and interpreted for patients selected for group 1 (with ocular PEX) and group 2 (without ocular PEX). The research project was completed in two years with data available in 2013. It was a project carried jointly by University hospital and Ministry of Health and family affairs.

Methods:

Patients aged 40 years and above amongst 1277 recruited subjects were selected for screening of ocular PEX. A total of 82 patients (36 with ocular PEX and 46 without PEX) were enrolled in our study. Ocular PEX was diagnosed by slit-lamp examination after dilating the pupils with tropicamide 1%. Body mass index was measured using standard methods. Body fat percentage was assessed using electrical impedance. Biochemical tests included fasting plasma glucose and plasma glucose 2-hours after 75 grams oral glucose load; fasting and 2 hrs serum insulin levels; fasting total serum cholesterol and high density lipoprotein and triglycerides. The Homeostasis Model Assessment was used to evaluate insulin resistance. All biochemical tests were done the same day of sample collection or frozen at -80oC till done, using automated Beckman-Coulter equipment. Non-invasive measurements of forearm skin vasodilatation in response to acetylcholine and sodium nitroprusside were obtained with Moors Laser Doppler Perfusion Imaging using Iontophoresis. An acclimatization period of 30 minutes was given to the patients. The drugs enter the circulation through iontophoresis across a Perspex direct electrode chamber attached to flexor forearm. Laser Doppler perfusion imager provided a continuously scanning laser beam to produce color coded images of the microcirculatory perfusion.

Results:

We found few statistically significant differences in anthropometric, biochemical and endothelial cell function parameters between subjects with ocular PEX and those without PEX (group 2-control). Subjects with PEX had significantly higher age (P=0.002), were less obese, had lower BMI (P=0.002) and less %fat (P=0.009) compared to subjects without PEX. Fasting and 2hr glucose and all lipid parameters were similar in both groups. However leptin, fasting and 2hr insulin, and insulin resistance measured as HOMAir were significantly lower in subjects with PEX. Finding of low leptin can be explained with low BMI and %fat. On chi sq test, PEX showed significant association only with glucose criterion and not with other criteria like waist, blood pressure, triglycerides, and high density lipoproteins. There was no significant difference between average acetylcholine response between two groups, however, patients without PEX had better average nitroprusside response compared to patients with PEX (P=0.002). No differences in anthropometric, biochemical and endothelial function parameters were surfaced when subjects with PEX were further classified into those with PEX glaucoma and without PEX glaucoma.

Conclusions:

Pseudoexfoliation is an age-related disorder believed to be a degeneration of the basement membrane. Endothelium is an important mediator of vascular tone and PEX has been reported to affect the blood vessels as well. The endothelium may be target of several disease processes like inflammatory, toxic, metabolic, traumatic and immunologic with adverse consequences. PEX is known to affect the morphology and physiology of corneal endothelium. It remains to be proved whether PEX affects vascular endothelium as well. Changes in the characteristics of vascular endothelium might be early markers of an ocular disease process like PEX syndrome or vice-versa. Leptin is an adipose-derived hormone that influences the total amount of fat in the body. Both leptin and PEX are encoded (markers) on chromosome 7, thus bearing a possible, yet unproved relation between the two. Pseudoexfoliation appears to be a systemic disease and may have association with both normal and abnormal, multiple body functions like anthropometric, biochemical, metabolic and physiologic as this research has revealed. The association of obesity, BMI, leptin, insulin resistance, triglycerides and lipoproteins with ocular PEX has not been studied so far. Finding a significant relationship between age, BMI, percent fat and endothelial cell function in PEX patients in this study signifies systemic manifestations of PEX. Further large studies are required to support our findings. FINANCIAL INTEREST: NONE