Study will include adults with abnormal visual fields. Half of them will be given either methylphenidate 10mg 2 hours before repeating the visual field test. the rest will serve as controls. All Subjects will also have a complete eye examination, a short questionnaire and a questionnaire to screen for attention deficit disorder. The investigators will compare the visual field results between the 2 tests.

Healthy adults with abnormal visual fields will be offered to participate Subjects will have a complete ophthalmic examination including dilated fundus examination.

Subjects with clear explanation for a visual field defect (e.g. optic neuropathy or retinal disorder) will be excluded from the study the subjects will be randomly assigned to the study group and control group using a 1:1 allocation.

Subjects in the study group will be provided with a single tablet of methylphenidate 10 mg to be taken orally 2 hours before repeating their visual field test.

The control group will not receive any placebo Both groups will repeat their visual fields. Both groups will fill out a short questionnaire to evaluate their experience in the second visual field test.

The study group will also fill out a screening questionnaire to rule out previously undiagnosed attention deficit disorder.

Two experienced ophthalmologists will separately interpret the visual fields results and compare the first and second visual fields of each subject, while being blinded to which group he was in.

Subjects will be provided with their test results and the ophthalmologist interpretation.

Inclusion Criteria:

• abnormal visual fields
• must be able to swallow pills

Exclusion Criteria:

• psychiatric disorder
• dementia
• ocular disorder which is known to cause abnormal visual fields
• prescription of psychoactive medications
• visual acuity lower than 20/100
• cardiac arrhythmia
• hypersensitivity to methylphenidate
• prescription of warfarin