prescribing for presbyopia
Solving Issues That Affect Multifocal Contact Lens Fitting
BY DAVID W. HANSEN, OD, FAAO
Large pupils, dry eyes, blepharochalasia and ptosis are all challenges that can interfere with multifocal contact lens success. Conquering these issues will bring you a step closer to designing successful multifocal and bifocal contact lenses for your patients.
Prescribing for Pupil Size
Pupil size is probably the most important ocular characteristic in selecting the appropriate presbyopic design. Large pupils that measure more than 4mm under mesopic conditions present the ultimate challenge because the dilating pupil will produce entopic phenomena with glare, flare, reduced visual acuity and poor translation from distance to near.
For patients who have large pupils, fit expanded aspheric GP distance zones that you can customize such as VFL-3 (Conforma Contact Lens); large distance translating GP designs such as Essential Extra (Blanchard Labs), Presbylite II (Lens Dynamics), Tangent Streak (Fused Kontacts) and ESSential-Solution (Blanchard/X-Cel); and soft lenses such as Focus Progressives (CIBA Vision), Frequency 55 Multifocal (CooperVision) "D" lenses, Bicon (Westcon) lenses with larger zones and C*Vue (Unilens).
Hydrogel lenses that have a center-near design, such as Frequency 55 Multifocal "N" lenses, Bicon lenses and Sunsoft Additions (Ocular Sciences, Inc.) usually provide better near vision as the pupil constricts. Small pupils in mesopic conditions are advantageous for these designs.
Remember to educate your multifocal patients about the side effects of pupil changes in different illumination settings. I tell patients that five major environ mental conditions may reduce acuity with these lenses: malls with high ceilings and fluorescent lighting (which presents artificial illumination); churches and synagogues; night time driving conditions; long corridors with fluorescent lights; and rooms with ambient light. Suggest that patients turn on a "map light" in the car when driving at dusk or after. Also, instruct patients to sit near a lamp in the family room -- many patients have a "special chair" for watching TV that doesn't provide good light for reading. These and other suggestions can help with multifocal lens success.
Managing Aging Eyelids
It's not your imagination -- your patients' eyelids are changing every year. Dermatochalasia, blepharochalasia and ptosis are just a few aging changes that can affect multifocal lens success.
Carefully assess a patient's lids to avoid future unnecessary contact lens modifications or reorders. I suggest measuring the external eyelid positions with a slit lamp set at 10X using an eyepiece reticule. This provides consistent and reproducible measurements for future comparison when eyelid surgery is warranted. Successful GP multifocal patients can become nightmare cases if you don't diagnose and treat progressive eyelid abnormalities before they become an aggravation.
How Dry Eye Am
For your dry eye presbyopes, investigate the etiology of the condition. The medical history should assess the patient's systemic health, identify medications and assess his environmental conditions. Look for collagen vascular disease and peri- and post- menopausal ocular dryness before fitting multifocal contact lenses.
Try ocular lubricants, punctal occlusion, cyclosporine ophthalmic drops or systemic supplements such as flaxseed oil and Omega 3 oils for symptomatic dry eye relief.
Diligence Pays Off
Do yourself a favor -- take the time to troubleshoot presbyopic patients first so you can save time during the lens fitting.
Dr. Hansen, a diplomate and fellow of the American Academy of Optometry, is in private practice in Des Moines, Iowa.