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Glossary

238 terms

From aberrant regeneration to zylonite, find concise definitions of ophthalmic terms and optical concepts.

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sixth nerve palsy

A sixth nerve palsy is weakness of the lateral rectus, the only muscle the abducens nerve supplies. It produces an esotropia in primary position that is largest on gaze toward the affected side and at distance, with limited abduction, normal adduction and a pupil that is never involved.1,3

Sources (5)
  1. Kanski, Clinical Ophthalmology (2024), ch. 19
  2. Liu, Volpe and Galetta, Neuro-Ophthalmology, ch. 15
  3. Yanoff and Duker, Ophthalmology (2023), ch. 9
  4. Pickwell's Binocular Vision Anomalies, ch. 17
  5. von Noorden and Campos, Binocular Vision and Ocular Motility, ch. 20

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Handouts

9 PDFs

Everything from Amsler grids for your patients to clinical guides and tables to use in your practice.

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Diopters to Radius Conversion Chart

1 page

Keratometry readings from 34.00 to 56.25 D converted to radius in mm, with both formulas and where 337.5 comes from.

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NBEO®* Part I Prep

1,816 questions

Timed practice exams with worked explanations and a score breakdown by topic. The first half of Exam 1 is free.

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EyeKnow O.D. Pro adds 3 more full-length exams and custom drills from all 1,816 questions. $179 for 12 months, intro price to March 18, 2027. See Pro plans →

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