Detection Of Specific Difficulties Of Retinoscopy Including The Types Of Refractive Errors Using Retinoscope Among The Students Of The Islamic University Of Gaza- Palestine

Yassin Al-nouno and Sami Shublaq department Faculty of science

Introduction The technique of retinoscopy is used to objectively determine the refractive status of the relative to the point of fixation. Retinoscopy is usually the first technique performed during the ocular examination that determines the patient's refractive status, and it is immediately followed by the subjective refraction. Some refractions are easy; some are extremely difficult. So the special difficulties need the supervision of competent optometrist.

Objectives : 1. The prevalence of special difficulties in retinoscopy among a group of (IUG) students. 2. To determine differences in refractive errors according to types and sex. Material and Methods: Study subjects comprised 1116 students. Males represented 33% (n=369) while females represented 67% (n=747) study was conducted between 1 October 2009 to 31 March 2011. (Table 1) We checked sex, age, address, vision without glasses and the visual acuity with glasses. The results showed that 937 cases (84%) were within normal "emmetropic cases", on the other hands, 179 cases (16%) were found to be abnormal "ametropic cases", they needed correction. The age of all cases was 18-24 years

Table 1 : Distribution of the study group according to sex No Classification Total Percentage 1 Males 369 33% 2 Females 747 67% Grand total 1116 100% Table 2 : Refractive errors among cases No Types of refractive errors Total Percentage 1 55 30.73% 2 Hypermetropia 7 3.91% 3 9 5.03% 4 Myopic astigmatism 104 58.10% 5 Hypermetropic astigmatism 4 2.23% Grand total 179 100%

A total of 23 cases “12.84%” showed with special difficulties in retinoscopy out of 179 cases who suffered from refractive errors. (Table 3) Males represented 30.43% (n=7) while females represented 69.57% (n=16) Table 3 : Shows the types of difficulties

No. Types of difficulties of retinoscopy Total Percentage 1 Faint red reflex (very high refractive errors) 9 39.13% 2 Spherical aberration 1 4.35% 3 Mixed aberration (Scissor Shadow) 6 26.09% 4 Squinting eye 1 4.35% 5 Immature cataract 0 0% 6 Conical 2 8.69% 7 Irregular astigmatism 4 17.39% Grand total 23 100%

Conclusion and recommendations: The special difficulties in retinoscopy are common among cases in the following order; very high refractive errors, scissor shadow , irregular astigmatism and keratocouns . Some cases of special difficulties are caused by some eye diseases that may cause negative effect in retinoscopy such as cataract, ulcers in the eye media and tilting of the crystalline lens. The optometrist should do subjective check after retinoscopy. All of cases who suffer from special difficulties need regular follow up under the supervision of competent optometrist. The classifications according to the gender were made just as a normal classification, and we don't want to use it for improving any scientific facts.