This study is a prospective, single crossover, double-masked, controlled clinical trial that will use topical brinzolamide (Azopt)ophthalmic medication to try to improve the nystagmus and visual consequences of nystagmus in patients with infantile nystagmus syndrome (INS). Subjects will undergo a clinical exam, questionnaire and eye movement recordings on day 1 and then receive either topical Azopt or placebo three times a day in both eyes for days 2,3 and 4 followed on the morning of day 5 by a repeat clinical exam, questionnaire and eye movement recordings. After at least one week, this protocol is repeated with the crossover regimen being taken by the subject. One week after all medications are discontinued, another clinical exam is done before study discharge. The hypothesis is that nystagmus and associated visual symptoms will be improved while on the Azopt compared to the placebo. There will be a total of 5 visits over a 1-2 month period.

5 subjects are expected to be enrolled in the study. Each subject will be in the study for approximately 1 month.

Efficacy will be assessed by:

• ETDRS Visual Acuity Testing of Binocular Best Corrected Visual Acuity In The Nystagmus Null Zone
• The Validated Amblyopia & Strabismus Ocular Motor Questionnaire
• Eye Movement Recording Data Analysis of The Nystagmus Waveform

Safety will be evaluated by:

• Ocular signs and symptoms
• Visual acuity (uncorrected and best corrected)
• Slit lamp exam and Intraocular Pressure
• Systemic signs and symptoms

Inclusion Criteria:

• Age; greater than 12 years old and able to cooperate for full study protocol
• Subject able to understand and sign informed consent
• Subject able to participate in complete ophthalmic and ocular motility evaluation
• Subjects with Infantile Nystagmus Syndrome diagnosed by clinical evaluation and eye movement recordings
• Best-binocular visual acuity in null position 20/50 to 20/200 inclusive using ATS or ETDRS vision testing
• Subject/family able and willing to make the required study visits
• No previous ophthalmic treatment for nystagmus other than for refractive error

Exclusion Criteria:

• Any current use of systemic or topical medications (traditional or non-traditional)
• History of ocular surgery, trauma or chronic ocular disease other than amblyopia
• Systemic diseases requiring medication or other treatments that are known to affect the ocular motor system (e.g., depression, seizure disorders, psychosis)
• Behavioral or neurological disorders which interfere with the study
• Physical or mental impairment precluding study compliance
• Participation in any study involving an IND investigational drug within the past year
• Individual (female) is pregnant, nursing or planning a pregnancy (The safety of Azopt for use during pregnancy has NOT been determined.)
• Periodicity or aperiodicity of INS present on eye movement recordings
• Allergy to sulfa or other components of Azopt solution