Evaluation of level of stereopsis of ophthalmologists
Keywords:Stereopsis,, Ophthalmologists, Stereo acuity, Bead task, Monocular and Binocular conditions
PURPOSE: To evaluate the status of stereopsis among ophthalmologists.
METHOD: A cross sectional study was conducted involving 42 ophthalmologists including post graduate residents, medical officers, senior registrars, associate professors and head of department working at Ophthalmology department Mayo Hospital Lahore. Their best corrected visual acuity (BCVA) was recorded. Gross stereopsis was checked by Lang 2 pencil test, Lang 1 and Lang 2. Moderate level of stereopsis was assessed by a standard Frisby test at 40 cm. TNO stereo test was used to find out the level of fine stereopsis. Qualitative and Quantitative values were recorded. A bead task was also performed under monocular and binocular conditions. Participants had to thread fixed number of small beads in a small needle in a 50sec time duration with a help of needle holder and forceps. Results were recorded on a self-designed proforma.
RESULTS: Gross stereopsis was assessed by Lang 2 pencil test present in all participants. 7.1% had stereopsis of less than 550 seconds of arc on Lang 1 and less than 200 seconds of arc on Lang 2. On Frisby stereo test normal stereopsis of 85 seconds of arc was present in 88.1%. Reduced stereopsis of 170 seconds of arc was found in 9.5% and 2.4% had no stereopsis on Frisby. Only 16.7% Ophthalmologists have normal 60 seconds of arc stereopsis on TNO. Borderline stereo acuity of 120-240 seconds of arc was present in 57.1%. Reduced stereopsis of 480 seconds of arc was found in 7.1%. While 19.0% of the ophthalmologists had no quantitative value of stereo acuity and were stereo blind. Bead task was performed under monocular and binocular conditions. Correlation was significant between TNO and number of beads with one eye (p<0.001) (r=0.565) and no. of beads with two eyes (r=0.706) (p<0.001). Lang 2 and number of beads with one eye(r=-0.342) (p=0.027) and number of beads with two eyes(r=-0.475) (p<0.001) also showed significant correlation. No significant correlation was present between Frisby test and bead task (r=-0.231) (p=0.141).
CONCLUSION: Most of the ophthalmologists had good stereopsis and they performed the bead task better as compared to those with reduced stereopsis.
KEY WORDS: Stereopsis, Ophthalmologists, Stereo acuity, Bead task, Monocular and Binocular conditions