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Nice Niche!
Short corridor PALs offer a great solution for many specific fitting challenges
By Karlen McLean, ABOC, NCLC

SWEET PETITES

Small frame designs usually feature less depth and more width than larger frames, causing wearers to adjust their viewing habits.

Large frame wearers tend to move their eyes more and their head less. Studies show that large frame wearers rotate their eyes 35 degrees and head 25 degrees when moving from distance to near viewing, while small frame wearers move their eyes only 20 degrees and head 40 degrees to make the same transition. This necessitates two key areas of design for short corridor PALs: Supplying enough space for a usable reading area and providing less distortion in the lens' periphery.

■Adaptation. If a patient is accustomed to traditional multifocals or standard PALs, he/she may be used to having more viewing area and farther range in viewing habits.

Patients who are making the transition to short corridor PALs should be informed that their field of view will be lessened, and that they are likely to have to target their point-of-focus more precisely. 

■Making it work. ECPs should also take time to hone short corridor PAL measurements, like PD, OC, and seg height, to exact specifications. After pre-adjusting the frame, a monocular PD should be taken with a pupilometer. OC is measured with the patient sitting at the same height as the dispenser while looking straight ahead. The pupil's center is dotted precisely on each demo lens. Seg height should adhere to manufacturers' recommended fitting heights.

Seg height should adhere to manufacturers' recommended fitting heights. Image courtesy of Essilor

Short corridor PALs are typically recommended when a frame has a vertical ("B") measurement of less than 40mm. This is true when fitting any smaller frames.

For the best results, preadjust frames to an even level on both eyes and align nosepads. Adjust pantoscopic tilt to between 10 and 15 degrees, as recommended by the manufacturer. Confirm that temples and frame front are fitted properly before taking measurements.

CHILD'S PLAY

Kids and teens who need distance and near-vision correction are candidates for short corridor PALs with low recommended fitting heights.

First-time PAL wearers are the best candidates for short corridor lenses because they don't have any prior usage habits. Images provided by Shamir (top) and Hoya (below)

■Looking good. While some ECPs fit kids in flattop multifocals due to vision therapy or lifestyle factors, many ECPs recommend PALs for kids for cosmetic benefits: With PALs, others don't know the child or teen is wearing multifocals, which eliminates or reduces the stigma of wearing "old people's glasses."

■Making it work. Some ECPs fit kids' PALs a few millimeters higher than normal for specific visual therapy. Because kids are so adaptable, they usually easily adjust to wearing PALs.

However, as when fitting all short corridor PALs, the add power should not be bumped, as increasing add power by even 0.25D will unnecessarily increase the hardness of the PAL design and may constrain viewing range and usage.

KEEPING OCCUPIED

Occupational, office, or computer lenses often fall into the short corridor category with lower recommended fitting heights. Distinguish between regular short corridor PALs and workstation PALs; and, fit workplace-specific PALs for office use, then a second pair of short corridor PALs for everyday.

■Computer conscious. The new generation of workstation PALs offer enhanced near and intermediate vision, with a small distance viewing area—about 10 feet away. These PALs help ease Computer Vision Syndrome symptoms and enhance workplace comfort and performance.

■Making it work. To fit office PALs, have the patient remain seated and work with them in a desktop setting, using a computer to simulate their workstation. When dispensing, reeducate them on proper use of their lenses, including verifying near vision using a reading card, intermediate vision using a computer screen, and distance vision by viewing a clock or poster up to 10 feet away.

Remind patients that workstation PALs are specially designed for work tasks and not to be used for any other activity, like driving.

SEEING SENIORS

Short corridor PALs come in many materials. Image courtesy of Seiko Optical Products

Seniors want fashionable small frames and can enjoy smaller frames and short corridor PALs if educated up front about how they work.

■Adaptation. Seniors and long-time traditional multifocal wearers' eyes typically transition less quickly from distance to intermediate to near than someone with younger eyes. And, they're accustomed to using more intermediate zone than short corridor PALs offer.

Explain that when selecting small frame and PALs, they may notice they have to look more directly at what they're viewing to get the most out of their wearing experience.

■Making it work. Initially, they may be more aware of the parameters of the frame and peripheral blur of the lenses. Point out that they'll enjoy their new downsized eyewear for the comfort. Smaller lenses, especially in lightweight and thinner lens materials like poly, Trivex, or high-index, help the sensitive, thinning skin around the nose by lifting pressure from the bridge area.

The better appearance of smaller, thinner lenses is another perk. ECPs can also target patient-specific lifestyle requirements as a short corridor PAL benefit, including tighter focus when playing games and cards, some hobbies and sports activities, and reading.

EARLY PRESBYOPES

Early presbyopes and first time PAL wearers generally visually accept and enjoy short corridor PAL designs. Many of these patients use PALs for near and far tasks, while the intermediate area is used as a transition zone.

■Ready to wear. Many young presbyopes do well with short-corridor PALs since their eyes can quickly transition from zone to zone.

First-time PAL wearers are the best candidates, since they aren't preconditioned to using any other type of multifocal or PAL. This group usually selects fashionable small frames, so short corridor PALs are the standard go-to for lens selection.

■Making it work. Get these wearers jazzed about high-tech frame and lens selection, and talk technology early by simply explaining how short corridor PALs work.

This helps ease them gently into presbyopia, and with proper PAL design selection, lens measurement, fitting, and dispensing techniques, they're likely to be your biggest short corridor fans.