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November 2002
IN THIS ISSUE

Wavefront seeks a higher order of vision correction
New laser system for intraoperative measurement of LASIK flap thickness
Visual prostheses use neurotransmitter retinal chips to stimulate retinal function
Wavefront emerges as powerful tool for night vision
Allegretto promising for hyperopia and hyperopic astigmatism
Topography's role in wavefront systems
IOP measurement after LASIK may be unreliable
LASEK may only play support on refractive stage
Solid-state laser PRK yields favourable results for myopia
GTS-assisted DLK useful alternative to PK for keratoconus
Glaucoma common after PK bodes poorly for visual outcome
Classic drawbacks of PRK succumb to new strategies
New insight into LASIK dry eye pathogenesis
Use of anti-inflammatories after capsulotomy questioned
Good quality training leads to good quality cataract surgery
One line of regained visual acuity is a snip at just €120
Mitomycin-C provides effective haze prophylaxis
Long-term concerns linger on safety of Mitomycin-C
German politicos promise health reforms
Honey forms biblical basis for corneal oedema
Routine two-step LASIK after PK unnecessary
Plasma knife provides clean and accurate cut for capsulorhexis
Glaucoma therapy targets apoptosis and trabecular meshwork
Viscocanalostomy viable choice for cataract-glaucoma
Device allows needle-free injections into smallest vessels
New river blindness therapy may provide panacea for 18m people
Daytime running lights may soon be compulsory in all EU states
Intracorneal lamellar implants still a questionable option
Aqualase system viable for small incision cataract removal
Unilateral von-Hippel disease with optic nerve head
FEATURES
From The Editor
Reflections on Refractive Surgery
In Your Good Books
An Eye On Travel
Bio-ophthalmology
Outlook on Industry
Regulatory Matters



Wavefront emerges as powerful tool for night vision

By Ana Hidalgo-Simón MD, PhD

NICE - Night vision complaints after LASIK surgery can be a patient's nightmare but surgeons may find the answer in wavefront-guided ablation.

Julian Stevens MD presented his experiences of using wavefront ablation to re-treat 34 eyes reporting glare and other night vision problems following otherwise successful LASIK procedures.

Night vision problems were confirmed using Oculus Mesometer night vision testing. All patients underwent wavefront scanning, PreVue lens cutting and vision testing, and wavefront guided ablation using the Visx excimer laser.
Preoperative aberrometry revealed significant high order aberrations, with a mean of 0.68. At months one and three postoperatively, the mean dropped to 0.58.

These values were not uniformly distributed across the group. Some patients had a "spectacular reduction" in aberrations, while others changed very little or even experienced a small increase, Dr Stevens said.

"We are conducting a prospective study of wavefront-guided LASIK to treat 100 eyes of 100 patients who have had reduced quality night vision. What the re-treatment actually does is to enlarge the effective optical zone after previous LASIK," Dr Stevens explained.

Objective night vision assessment using the Oculus system confirmed that the average night vision had improved at one month after treatment, but the improvement recorded by the test was bigger after three months. There is a period of accommodation in which night vision continues to improve, he explained.

Dr Stevens and his colleagues used a questionnaire to assess subjective improvement with the treatment. On the whole, patients were very satisfied with the results of the re-treatment: 48% responded that wavefront surgery had significantly improved their night vision and 38% reported some improvement.
Only 10% considered their night vision to be about the same and 5% believed it had worsened.

A month after wavefront therapy, 86% of patients found driving during daytime to be good or excellent. Only 5% described it as fair and 10% as poor.
A total of 63% of patients regarded the quality of their vision good, very good or excellent while driving at night against oncoming headlights. A further 32% said it was fair and 5% poor.

When asked if their overall sharpness and acuity of vision was better before or after wavefront surgery, 90% of patients said it was better after the second operation.
That percentage was a more modest 86% when asked if vision for driving in daylight was better after the second operation.

Overall satisfaction with wavefront surgery was rated excellent by 57% of patients; very good by 14%; good by 19%; and fair by 10%. Nobody rated the experience as poor.

"One of the most frequent questions I am asked by patients considering undergoing LASIK refractive surgery is 'what will happen to my night vision?' Up until now I did not have a satisfactory answer. Now I say: 'There is a 90% probability of wavefront surgery correcting night vision difficulties should they arise.'"

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