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Br J Ophthalmol. 2001 September; 85(9): 1057–1060.
PMCID: PMC1724124

Anomalies of binocular function in patients with longstanding asymmetric keratoconus


AIMS—To study binocular function in patients with longstanding asymmetric keratoconus.
METHODS—In 20 adult patients with longstanding asymmetric keratoconus managed with a scleral contact lens a full clinical and orthoptic assessment was performed with and without the scleral contact lens in the poorer eye.
RESULTS—All 20 patients had a corrected acuity of at least 6/9 in their better eye. With the scleral lens in situ the acuity of the poorer eye ranged from 6/6 to 6/60 and without the lens from 6/18 to hand movements. Patients were aged from 18 to 68 years and had worn a scleral contact lens for between 3 and 106 months. Without the contact lens in their poorer eye all patients had a small exotropia and all showed suppression, with the exception of one patient who had a right hypertropia with diplopia. With the scleral lens in situ 12 patients had an exophoria or esophoria, six a microexotropia, and two a manifest exotropia with suppression.
CONCLUSIONS—Binocular function breaks down in some adult patients with longstanding asymmetric keratoconus. This is probably caused by longstanding unilateral visual deprivation. There are similarities to the breakdown of binocular function seen in some patients with a longstanding dense unilateral adult onset cataract who can develop intractable diplopia following cataract surgery.

Figure 1
Age at diagnosis of keratoconus, duration of disease, and duration of scleral contact lens wear for 20 patients.
Figure 2
Comparing the median stereoacuity for Snellen acuities of the poorer eye between 6/12 and 6/60 (20/40 and 20/200) in 20 patients with longstanding asymmetric keratoconus with those for 14 normal subjects taken from table 1 of Goodwin ...

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