Special lens designs can address cosmetic, photophobia, lens thickness concerns

Issue: March 1998

BySusan E. Marren, OD FAAO

GUILFORD, Conn. - Many options are available today for patients who need special lens designs. Some patients need special lenses for cosmetic reasons; some need to reduce lens weight, aberration or thickness; and some require therapeutic reduction of photophobia.

For closed-head injury patients with photophobia, William V. Padula, OD, FAAO, in practice here, frequently prescribes Corning photochromic lenses. He uses the CPF series, 450, 511, 527 and 550 nm wavelengths. Higher numbers reflect denser lenses for the more photophobic patients.

These lenses are also prescribed for age-related macular degeneration and retinitis pigmentosa patients. When glass is too heavy, he uses plastic 10%, 20% and 40% lenses from NoIR Medical Technologies (South Lyon, Mich.). Although they are not photochromic, the tints are similar to the Corning lenses.

Vincent R. Vicci, OD, co-director of Vision Clinics for the Kessler Institute for Rehabilitation who is also in private practice in Cranford, N.J., uses photochromics of all makes for closed-head trauma patients. He also uses polarized lenses when he finds the patient's problem is not so much intensity, but glare.

After reading about epilepsy and working with patients who have seizure disorders, Dr. Vicci began using a blue-green tint for patients who had experienced a seizure and has found the tint helpful for many, especially when the patient's problems are exacerbated under fluorescent lighting. He orders about 15% blue-green, with "No Red" written underneath. When the lenses come back from the laboratory, he looks through them at an incandescent lamp and rejects them if he notes red.

According to Clifford W. Brooks, OD, FAAO, who teaches ophthalmic optics at Indiana University School of Optometry in Bloomington, from an optical standpoint, aspherics are not absolutely necessary until the prescription reaches +7 D, but he recommends them for patients with much smaller prescriptions, depending on the frame size and shape. He reports aspherics are used not just for optical purposes, but also for lens flattening and thinning. If a lens will be too thick, an aspheric is the lens of choice for plus prescriptions and may be a strong contender for thinning minus edges as well.

High index

Robert J. Lee, OD, who is a clinician and teaches clinical optics and ophthalmic optics at Southern California College of Optometry in Fullerton, generally recommends high index lenses for prescriptions above 3 D. He agrees that asphericity is more of an advantage to plus wearers and points out that fitting the lenses closer to the face, that is, reducing the vertex distance, reduces the magnification and improves the appearance of the eyes in high plus lenses. This will also help the high minus wearers avoid the very small eye appearance. Aspherics also increase the field of view by minimizing distortions.

Dr. Lee directs patients with high prescriptions toward the smaller eye sizes and keeps the eyes centered in the frame to reduce the color fringes and off-axis blur. He also recommends anti-reflective coating on all aspheric and high index orders. He suggests optometrists and opticians work with their local laboratories and take advantage of point of purchase materials to show patients the differences that aspheric and high indices make.

Suggesting lens designs

Ed DeGennaro, professor of opticianry at J. Sargeant Reynolds Community College in Richmond, Va., suggests we ask questions about work and hobbies. "Do you use a computer at home or at work? Are there times when your eyes are more at risk? Do you ever read in an upward or outward direction?" And he always demonstrates what he means. He believes asking this last question will result in at least one out of 12 patients taking a double-segment multifocal.

To assess bifocal/trifocal needs in the workplace, he asks patients to demonstrate their working area on the optical counter in front of them. He asks, "Do you interview people across the table?"

Mr. DeGennaro also says to patients: "What would you say if I told you I had lenses that were comfortable in any light situation?" He loves his own Transitions 3 Progressives (Transitions Optical/Sola Optical) lenses, and he is also enthusiastic about what the future holds for double-sided aspheric progressives. With the "atoricity" comes a tremendous reduction in distortion and aberration. The lenses are high-priced but should do fairly well in an upper end optical shop, Mr. DeGennaro said.

Aspheric, polarized lenses

"Aspherics," Mr. DeGennaro said, "are good for just about anybody." He tells patients aspherics are "the latest in high-tech lenses that offer the finest benefits you can get." He likes high-index lenses for powers above +3 D or -3 D, and particularly likes those with an index of 1.6 or 1.66.

Mr. DeGennaro points out that Spectralite lenses (Sola Optical) have a high Abbe value, which is the greatest determinant of off-axis color distortion. He reminds us that polycarbonate is "always a good choice," because it is lighter than any of the most commonly used lens materials.

Like Dr. Vicci, Mr. DeGennaro likes polarized lenses that are now available in plastics. He feels they increase contrast to give better visual performance.

For Your Information:

William V. Padula, OD, FAAO, founding president of the Neuro-Optometric Rehabilitation Association and author of Neuro-Optometric Rehabilitation (Optometric Extension Program Foundation, 1994), may be contacted at Shoreline Vision Rehabilitation, 652 Boston Post Rd., P.O. Box 1748, Guilford, CT 06437; (203) 453-2222; fax: (203) 458-3463; e-mail: BPadula@SVPC.com.

Vincent R. Vicci, OD, is president of the Neuro-Optometric Rehabilitation Association. He may be contacted at 123 North Union Ave., P.O. Box 904, Cranford, NJ 07016; (908) 272-1133; fax: (908) 272-2360.

Clifford W. Brooks, OD, FAAO, is associate professor at Indiana University School of Optometry, 300 East Atwater Ave., Bloomington, IN 47405; (812) 855-1298; fax: (812) 855-8664. He is co-author of System for Ophthalmic Dispensing, second edition.

Robert J. Lee, OD, may be reached at Southern California College of Optometry, 2575 Yorba Linda Blvd., Fullerton, CA 92831; (714) 449-7491; fax: (714) 879-9834. None of the above doctors has a direct financial interest in the products mentioned in this article, nor is any a paid consultant for any company mentioned.

Ed DeGennaro can be reached at P.O. Box 85622, Richmond, VA 23285; (804) 786-1375; fax: (804) 786-5298; e-mail: eddege@I2020.net. He is a consultant to Sola Optical and co-chair of the Vision Expo conference program.

Susan E. Marren, OD, FAAO, is an assistant professor at the Eye Institute, 1201 Spencer, Philadelphia, PA 19141; (215) 276-6160; fax: (215) 276-1329; e-mail: SMarren@aol.com. Dr. Marren has no direct financial interest in the products mentioned in this article, nor is she a paid consultant for any companies mentioned.