PREVALENCE OF NON STRABISMIC VERGENCE DYSFUNCTIONS IN AN ORTHOPTIC CLNIC
INTRODUCTION
In the preceding generations, fine distance visual acuity and stereoscopic vision were of paramount importance, since the survival depended absolutely on the capability to farm, hunt and fish. But today, the emphasis has shifted virtually from distance visual functions to two dimensional near visual tasks such as desk work, reading, computer usage etc.The presence of non strabismic binocular dysfunctions such as accommodative and vergence anomalies make it difficult for the visual system to perform these kind of activities with accuracy and effortlessness. When persons, who are in short of suitable accommodative and vergence amplitudes, are involved in near visual activities, they may develop ocular symptoms that may further impinge on their visual performance.
Indian literature has no significant number of studies that have been conducted to determine the prevalence of vergence dysfunctions and there is a lack of consensus in the scientific literature on what diagnostic criteria should be used to define each anomaly. Prevalence of a disorder refers to the total number of cases of a disorder or a disease that exists in the population, either during a period of time or at a specific point in time1.Prevalence data provide valuable information to health care professionals, enabling them to allocate resources efficiently and to plan effective diagnostic approaches, treatment options, preventive measures and in conducting public awareness programmes. Proper epidemiological information based on scientific evidence can help in many areas such as decision-making in certain clinical initiatives.
In a clinical trial to determine the prevalence of bi...
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...s. The table 1 shows the classification criteria used in this study for categorizing vergence dysfunctions.
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The thresholds used to calculate each mean were not highly variable between trials. The data recorded over each trial were highly consistent between one another, except for a slight deviation in the measurements recorded on the palm of the hand. During ascending trial three on the palm, the results deviated from the norm in reference two the two prior trails. On trial one and two, 0.05 was the only measurement that was not felt. On trial three, not only was 0.05 not felt, but 0.10 was also not felt, which deviated from the norm set forth in the two prior
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When comparing quantitative measures such as gravimeter with visual analog scales, the quantitative measures, subjective ratings have a relatively high level of diagnosis sensitivity and specificity (48,49B). This method, however, is preferably used in research field, and is rarely used in clinical practice.
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Robert, a 65 year-old male, has trouble reading fine detail, especially out of his central vision. He complains that his vision is blurred and that it is harder to see while operating a motor vehicle. In addition, sometimes objects appear wavy or crooked, which impairs his vision. His worst symptoms were that he occasionally lost the ability to distinguish between the features of familiar faces and he had a localized blind spot. Robert is not alone; many people suffer from symptoms related to loss and distortion of the visual field. He suffers from macular degeneration, the leading cause of decreased vision loss in the United States, especially for people over the age of 50 (Philippi, 2000).
Regarding to the ocular examination, the patient's visual acuity without optical correction (spectacle) was good 20/20 in both eyes. IOP measurements was 18 mmHg on the right eye and 16 mmHg in the left eye. The pupil was equal, round and reactive to light with no afferent pupillary defect in both eyes. In extarocular movement test, there was limited downward gaze with
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