GP Lens Case Grand Rounds Troubleshooting Guide – 16

Early Presbyopia (Non-GP Wearer): Douglas P. Benoit, OD, FAAO

Background

Patient BC, a 47-year-old secretary, was currently wearing soft spherical lenses in a monovision configuration (right eye distance). She complained of blurry vision relative to her glasses, and felt that her near vision was not optimum. Her current glasses had 0.75 D cylinder power OU. The options of GP multifocals or soft toric lenses, in monovision or multifocal designs, were discussed.

Test Procedures, Fitting/Refitting, Design and Ordering

Manifest Refraction:

OD: -1.75 -0.75 x 180
OS: -1.00 -0.75 x 180
Add: +1.25D

Keratometry:

OD: 42.87@180; 43.50@090
OS: 43.25@180; 43.87@090

The left eye was dominant and this patient had a vertical fissure height of 10.5mm. The upper lid overlapped the superior limbus by 2mm and the lower lid was tangent to the lower limbus. The pupil diameter was 4mm in normal room illumination.

The initial trial fitting was performed with the assistance of a topical anesthetic. These lenses, as with many GP multifocals in common use today, are fit slightly steeper than “K.” The following lenses were fit:

Lens Design: Essential GP Series 2 (Blanchard)

Base Curve Radius: OD 7.80mm; OS 7.70mm
Overall Diameter: 9.50mm OU
Power: -2.00D OU

The distance visual acuity: OD 20/20 with a -0.25D over-refraction and OS 20/20 with a +0.50D over-refraction. The near vision was 20/20 OU with the aforementioned over-refraction. The position in primary gaze was lid attached OU, with the right lens slightly higher. The lens movement was good in all positions of gaze, with good translation up on downgaze. Fluorescein showed central alignment OD while the left lens exhibited slight apical clearance. Both lenses showed good peripheral clearance. By the conclusion of the diagnostic fitting process, the anesthetic had worn off and the patient reported good comfort.

The Following Lenses Were Ordered:

Essential GP Series 2 (Boston ES material)
Base Curve Radius: OD 7.80mm; OS: 7.70mm
Overall Diameter: 9.50mm OU
Power: OD -2.25D; OS -1.

Patient Consultation and Education

The new lenses were dispensed and the patient reported good comfort after 10 minutes of lens wear. The vision was 20/20 at distance and near. A lid attachment fitting relationship was present with good movement and translation OU. Instruction and practice on insertion and removal was provided.

The possible need to make changes in lens parameters to enhance the fitting relationship and/or vision was provided. Proper care and compliance, including indicating to her the importance of avoiding a tap water rinse prior to insertion, was provided.

The patient was instructed on proper head position and need to blink normally, especially while reading. A gradual increase in wearing time was recommended.

Follow-Up Care/Final Outcome

At the one week progress evaluation, the patient was satisfied with her comfort and wearing time. The vision was 20/20 at all distances. The position and movement were similar to that found at the diagnostic fitting and this patient has continued to do well.

Discussion/Alternative Management Options

While this patient was an excellent candidate for an aspheric GP multifocal, it is possible that a segmented bifocal GP could have been used. This would have been beneficial if near vision demands were very high or if the pupils were larger than normal in room illumination. It would also be possible to use a soft toric lens in either a monovision arrangement or a bifocal. Comfort should be good immediately, but there is the compromise of depth perception sometimes experienced with monovision, while the toric soft bifocal/multifocal can provide less acute vision while also representing a relatively expensive non-disposable option.

It should be noted that the patient was left eye dominant but the previous monovision attempt used the right eye as the distance eye. As a rule, the dominant eye should be biased for distance in both monovision and bifocal/multifocal cases.

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