Topography of Lasik Cornea with Poor Night Vision
The topographic images below are that of a young man who underwent LASIK surgery several years ago. His vision in bright daylight is very good. However, his indoor and night vision is very poor. The colored topographies of this young man’s eyes are not that interesting. Look at the size of his pupils. These images were taken in a low light environment. As you can see in these images, the diameter of his right pupil is 7.8 mm and his left pupil is 8.6 mm in diameter. A number of post-LASIK patients have written to me asking questions about LASIK and pupil size so I will attempt to make this controversy understandable. The diameter of a LASIK created treatment zone is 6.5 mm (more or less). In the earlier days of LASIK these treatment zones were much smaller. An 8.mm pupil diameter is considered to be extremely large. Also bear in mind that the cornea sits about 4.5 mm in front of the pupil. Because of this fact, the diameter of the treatment zone will need to be considerably larger than the diameter of the pupil in order for this patient to see clearly indoors and at night. (Think of a person with a large head wearing and looking through eyeglasses meant for a small child). This young man, to see clearly at night (assuming there are no other LASIK induced complications), will need a treatment zone approaching 12 mm. which is impossible to do. This is why many LASIK surgeons give their young patients eye drops to constrict their pupils. We fit this young man with a large diameter scleral lens with a large viewing area (optic zone). However, even this was unable to address completely this patient’s loss of quality vision at night. It is also important to understand that many of the LASIK created treatment zones are not directly over the pupil or the patient’s line of vision (due to a number of reasons). With patients with these conditions the only viable non-invasive treatment is a scleral lens. With additional surgeries (“enhancements”) patients run the risk of a number of unanticipated complications.
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