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Pupillometry is a critical part of pre-operative testing for laser eye surgery - and a part that LaserMyEye believes is riddled with problems.
It is necessary to establish the largest size your pupil is likely to get in dim light or dark in order to ensure that the laser treatment zone is at least that large. If the treatment zone is smaller than the pupil, there is a very high probability that you will suffer from night vision disturbances (NVD) after surgery.
Unfortunately, too often the patient's DAPD is NOT measured accurately - that is, the measurement is smaller than the reality, and so the patient is given a smaller treatment than needed to reduce the risk of NVD. The issue becomes further complicated by the fact that if the patient is getting LASIK, it may not be possible to safely give them a sufficiently large treatment zone for NVD prevention purposes because it might penetrate so deeply into the centre of the cornea that risk of ectasia is increased. Patients need to be fully aware of these kinds of tradeoffs before surgery and where appropriate consider surface ablation instead.
As a rough guide, note that for people aged 20-40 the average pupil size is nearly 7mm. Many patients, however, have pupils much larger than this - 8mm, 8.5mm or even larger. Patients with pupils larger than 7mm are especially prone to NVD, as are patients with high prescriptions. The combination of high prescription and large pupil is particularly troubling. |
