Evaluation of central, steady, maintained fixation grading for predicting inter-eye visual acuity difference to diagnose and treat amblyopia in strabismic patients.
BACKGROUND
Diagnosis of amblyopia in preverbal strabismic patients is frequently made by binocular fixation preference (BFP) testing. The reports on reliability of BFP are equivocal. This study evaluated the reliability of BFP testing in patients with horizontal strabismus.


METHODS
This prospective observational study included patients with manifest, horizontal, comitant deviation> 10 prism diopter (PD). Inter-eye acuity difference (IEAD) was calculated by converting Snellen visual acuity to logMAR and was compared with BFP testing. The fixation behavior of the non-preferred eye was evaluated by a single investigator as central or uncentral, steady or unsteady and maintained or unmaintained. Amblyopia was defined as the IEAD of> 0.2 logMAR.


RESULTS
Of total 61 patients 36 were females and 36 had convergent squint, mean age 9.8 years. The correlation of BFP testing with IEAD was good for esotropia and exotropia. The sensitivity, specificity, positive and negative predictive value of central, steady, maintained (CSM) grading was 93%, 78%, 79%, and 93% respectively. Sensitivity and negative predictive values were higher in children aged four to nine years and anisometropia> 1 diopter. The correlation between IEAD and lower grades of BFP testing was poor.


CONCLUSIONS
CSM grading for BFP testing is useful for the detection of strabismic amblyopia but not useful to differentiate the depth of the amblyopia.
Kothari
Mihir
M
Aditya Jyot Eye Hospital Wadala, Mumbai and Jyotirmay Eye Clinic and Pediatric Low Vision Center, Thane, Maharashtra, India. drmihirkothari@jyotirmay.com
Bhaskare
Amar
A
Mete
Deepali
D
Toshniwal
Svetlana
S
Doshi
Priti
P
Kaul
Shalini
S
D000293:Adolescent; D000550:Amblyopia / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D005403:Fixation, Ocular; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D013285:Strabismus / Q000150:complications*; D014792:Visual Acuity