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Degree of Deviation Causing Amblyopia in Squint Patients

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Degree of Deviation Causing Amblyopia in Squint Patients Section Ophthalmology Original Article Degree of Deviation Causing Amblyopia in Squint Patients 1Associate Professor; 2Assistant Professor; 3Senior Resident, Dept. of Ophthalmology; 4Environment Health and 1 2* 3 4 Safety Consultant, KD Medical College Kaiser Ali , Dhawal Agrawal , Malhar Vyas , Azra Ali Hospital and Research Centre, Mathura. ABSTRACT DOI:10.21276/iabcr.2018.4.2.25 Received: 05.11.17 Accepted: 27.11.17 Background: Cases of EXO and ESO deviation in various age groups and different sexes having central and eccentric fixation were taken. Materials & Methods: Out of 53 cases, 28 were of ESO. *Corresponding Author Of all the strabismic cases maximum number of cases reported in age group of 11-20 with male preponderance. if the angle required for superimposition was zero a patient with orthophoria had NRC and with heterophora had harmonious ARC. Measurement of objective angle of deviation was done Dr. Dhawal Agrawal by Hirschbergs method of corneal reflex and subjective angle of deviation with Maddox Rod test with Assistant Professor, Dept. of Maddox hand prisms. The angle of anomaly was calculated with Objective Angle- Subjective Angle. Ophthalmology, KD Medical College Hospital and Research Centre, Mathura. Results: Maximum number of cases in up to 15 degrees were of unilateral esotropia and in 16 to 20 degrees also the cases of unilateral esotropia were maximum. However, in above 30 degree the Copyright: © the author(s) and publisher. maximum number of cases were of unilateral exotropia. IABCR is an official publication of Ibn Sina Academy of Medieval Medicine & Sciences, Conclusion: Amblyopia once has set in then it is very difficult to correct it even if the angle of registered in 2001 under Indian Trusts Act, 1882. deviation is up to 15 degree. This is an open access article distributed in accordance with the Creative Key words: Amblyopia, Deviation, Strabismus Commons Attribution Non Commercial (CC BY- NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non- commercial. INTRODUCTION_____________________ Adaptation may be defined as a process of advantageous the benefit of binocular vision is lost due to disruption in variation and progressive modification whereby an organism alignment or due to optical state of eye binocular vision becomes adjusted to the conditions of life in harmony with annoyingly continues in the form of diplopia and visual environment. A sensory adaptation to an ocular deviation is confusion. the process in which a patient adapts to an interruption in normal binocular vision. It is an acquired physiological reflex METHODS__________________________ that develops during first several months of life. Its This study was done in Jawahar Lal Nehru medical college development demands certain requisite as each eye must be and hospital, Aligarh. The cases were selected from the capable of seeing and both eyes must be aligned within first refraction section and squint clinic of the institute of few years of life to present the projection of similar images ophthalmology, A.M.U. and Gandhi eye hospital, Aligarh. onto corresponding retinal areas. Once established binocular The patients consent was taken and the criteria for selection vision is retained as long as there is sight in both the eyes. If of cases were Access this article online How to cite this article: Ali K, Agrawal D, Vyas M, Ali A. Degree of Deviation Website: Quick Response code Causing Amblyopia in Squint Patients. Int Arch BioMed Clin Res. 2018;4(2):84- www.iabcr.org 86. DOI: 10.21276/iabcr.2018.4.2.25 Source of Support: Nil, Conflict of Interest: None International Archives of BioMedical and Clinical Research [84] April – June 2018 | Vol 4| Issue 2 www.iabcr.org Ali K, et al.: Amblyopia in Squint Patients 1. Patients complaining of eye strain, diplopia and inward eye. Amblyopia is a “developmental defect of spatial visual rolling of eyeball were taken up for study. The visual acuity processing that occurs in the central visual pathways of the for both right and 1left eye were recorded. brain.”[1] It presents most dramatically as loss of visual acuity 2. The degree of squint according to corneal reflex was at in one or, rarely, both eyes, but amblyopia is more than this; papillary margin 15 degree, between pupillary margin and certain forms of amblyopia also present with diminished limbus 25 to 30 degree and at limbus was 45 degrees. contrast sensitivity, Vernier acuity, grating acuity, and spatial 3. Those cases which had squint up to 15 degree and were localization of objects. in exodeviation, they were having maximum number of cases of amblyopia with central fixation. And this was true in Table 3: Shows Amblyopia on Degree of Fixation After esodeviation also of up to 15 degrees. Surgery AMBLYOPIA 4. The cases of deviation were studied whether they were AMBLYOPIA WITH TOTAL WITH CENTRAL having amblyopia and what type of correspondence ECCENTERIC FIX FIXATION RESULTS___________________________ ESO OF UPTO 15 12 8(15%) 4(7.5%) Table 1 shows distribution of cases according to degree of 16 TO 20 DEG ESO 8 4(7.4%) 4(7.4%) deviation. maximum number of cases in up to 15 degrees 21 TO 30 DEG ESO 6 3(5.6%) 3(5.6%) were of unilateral esotropia and in 16 to 20 degrees also the MORE THAN 30 2 - 2(3.6%) EXO UPTO 15 DEG 8 6(11.2%) 2(3.6%) cases of unilateral esotropia were maximum. However, in 16 TO 20 DEG EXO 6 6(11.2%) above 30 degree the maximum number of cases were of 21 TO 30 DEG _ _ _ unilateral exotropia. MORE THAN 30 6 2(3.7%) 4(7.5%) The table above shows the amblyopia according to degree DEG EXO of deviation. The degree of deviation less in ESO the amblyopia was more. In esodeviation of up to 15 degree the These defects may be explained by the mechanism of lack amblyopia was about 8 cases. In exodeviation similarly the of use of an eye because of media opacity or extreme deviation of up to 15 degree showed amblyopia of 6 cases. refractive errors that cause a chronically blurred image to form on the fovea of that eye; however, the cause of Table 1: Showing Distribution of Strabismic Cases According amblyopia in an eye that has strabismus is not as to Degree of Strabismus straightforward and is the result of abnormal binocular Alt Degree Total Ul ESO Ul EXO Alt EXO ESO interaction. Patients who have anisometropia and decreased Upto15 deg 23(43.3%) 12(22.6%) 0 8(15%) 3(5.6%) visual acuity in the more ametropic eye and who possess the 16 -20 deg 15(28.3%) 8(15%) 0 6(11.3%) 1(1.8%) sensory characteristics of monofixation syndrome are almost 21=30 deg 6(11.3%) 6(11.3%) 0 0 0 always amblyopic; the decreased acuity does not improve Above 30 deg 9 (16.9%) 2(3.7%) 0 6(11.3%) 1 (1.8%) totally with corrective lenses alone. These patients have 53 28(52.8%) 0 20(37.7%) 5(9.4%) decreased acuity, as measured using graded optotypes, gratings, and Vernier testing in the same proportion. This acuity loss extends to the peripheral visual field equally Table 2: Shows Amblyopia on Degree of Fixation Before nasally and temporally, which implies uniform degradation of Surgery the visual system by an amount proportional to the AMBLYOPIA AMBLYOPIA WITH anisometropia. As monocular visual function in the far TOTAL WITH ECC CENTRAL temporal periphery of the visual field is spared, the acuity FIXATION FIXATION defect found in the more central field must result from, in UPTO 15 DEG ESO 12 8(15%) 4(7,5%) some part, binocular interaction. 16 TO 20 DEG ESO 8 4(7.5%) 4(7.5%) Strabismic amblyopia may occur initially from birth to about 21 TO 30 DEG ESO 6 3(5.6%) 3(5.6%) 5.5years of age, but even if successfully treated it may recur MORE THEN 30 DEG 2 2(3.7%) until about 9 or 10years of age. The peak age for ESO development of fixation preference in strabismic children is TOTAL 15 13 about 1year of age (range 9 months to 2 years), but fixation UPTO 15 DEG EXO 8 6(11.2%) 2(3.7%) preference can occur until about 8–9years of age. Numerous 16 TO 20 DEG EXO 6 2(3.7%) 4(7.5%) publications describe successful improvement of visual 21 TO 30 DEFG EXO - - - acuity in strabismic or anisometropic amblyopia in older MORE THAN 30 DEG 6 2(3.7%) 4(7.5%) [7] EXO teenagers; the loss of the better-sighted eye has led to TOTAL 10(18.8%) 10(18.8%) spontaneous improvement in visual acuity in the remaining amblyopic eye of middle-aged adults! Perhaps the critical period for reversal of strabismic and anisometropic The table shows the amblyopia with different types of fixation amblyopia really has no end. after surgery.in esodeviation of up to 15-degree amblyopia The optic axis can be determined accurately only by with central fixation were more. In exodeviation amblyopia alignment of the Purkinje images with a coaxial light through with central fixation were more in up to 15 degrees of a telescope; this light intersects the retina between the disc deviation. and fovea.[1] For clinical purposes, the optic axis may be assumed to strike the fovea. An observer considers the eye to view along its pupillary axis, a line through the pupillary DISCUSSION________________________ center perpendicular to the cornea.
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