A CROSS SECTIONAL STUDY TO ASSESS THE CORRELATION AMONGST VISUAL ACUITY, CONTRAST SENSITIVITY AND VISUAL FIELD ANALYSIS IN PATIENTS WITH GLAUCOMA

Abstract

PURPOSE Over 80 million individuals worldwide suffer from glaucoma, which is the second most common cause of blindness. It is a group of illnesses which lead to blindness by loss of retinal ganglion cell leading to irreversible optic neuropathy. Therefore, basic approaches for glaucoma early diagnosis and enhanced strategies for stopping the disease's progression are crucial objectives of public health research that would benefit society. Progress in the visual field is an important outcome in determining the progress of glaucoma and modification of treatment. As such, methods for identifying advancement in the visual field have been the subject of research for many years. Contrast Sensitivity Scoring is based on the individual’s ability to delineate between objects based on the slight changes in luminance. Glaucoma can reduce contrast sensitivity for all grating sizes, mostly at the middle spatial frequencies. Visual Acuity testing involves the assessment of central vision hence other modalities of investigation are required in order to identify glaucoma at the earliest and supplement its treatment. METHODS At Sri Devaraj Urs Medical College, 41 patients in the ophthalmology department were evaluated as part of the study. Patients who met the requirements for study had their visual acuity assessed by using Snellens visual acuity chart , the obtained value was converted into a LogMAR value. By using Pelli Robson contrast sensitivity chart, the contrast Sensitivity was measured at a distance of 1 Meter. Goldmann Applanation Tonometry, 4-mirror gonioscopy, and slit-lamp biomicroscopy were xiv used to evaluate the anterior segment. Fundus lens + 90D used for optic disc inspection. After dilating the pupil, slit lamp biomicroscopy using Fundus lens and indirect ophthalmoscopy was used to determine the extent of damage, type and severity of glaucoma .The Humphrey visual field analyzer 24- 2 program was used to plot the patients' visual fields. SITA standard program was used. A measure called mean deviation, or MD, was employed to assess visual field function. A fault is considered early if its mean deviation is less than -6 dB, moderate if it is less than -12 dB, and severe if it is greater than -12 dB. Patients with the typical changes in the visual field and with optic nerve head changes, were diagnosed with glaucoma .If there are questionable optic nerve alterations but no discernible loss in visual field the patient was suspected of having glaucoma; if intraocular pressure (IOP) is 21 mm Hg or higher but there is no discernible loss in visual field or change in the optic nerve head, the patient is suspected of having ocular hypertension. RESULTS: The study in total included 41 people as sample. The age distribution revealed that 51–60 age the group was the most prevalent (48.8%), and that men slightly outnumbered women (56.1% vs. 43.9%). The largest occupational category was made up of clerks (39.0%), followed by tailors (17.1%). There was variation in visual acuity, with the highest acuity of 0.3 in both eyes. Results of the analysis of the anterior segment data were primarily within normal limits (WNL). Normal tension glaucoma (NTG) (22.0%) was the second most frequent type of glaucoma, after primary open-angle glaucoma (46.3%). The mean values of intraocular pressure (IOP) were found to be 24.71 mmHg for the right eye and 17.71 mmHg for the left, and the mean values of the Humphrey Visual Field Analyzer (HFA) mean deviation (MD) - 10.61 dB for the eye right and -8.33 dB for the eye left according to descriptive statistics. xv There is no clear relationship between contrast sensitivity and visual acuity for the right eye. The Pearson correlation coefficient between the CS score and the visual field analysis, a high positive link between the two with a P value of less than 0.001, indicating (HFA MD) is 0.613. Regarding the left eye: There is no direct association seen between the CS score and visual acuity. A statistically significant positive association between the CS score and visual field analysis (HFA MD) in the left eye is provided by the correlation Pearson coefficient of 0.342 and value P of 0.029 between the CS score and HFA MD. In order to minimize the impact of additional variables, the study was restricted to individuals with an excellent visual acuity score of (6/12) or higher. Eye disorders such as cataracts and other ocular conditions such as retinopathy ,age-related and diabetic maculopathy were excluded.