GP Lens Case Grand Rounds Troubleshooting Guide – 18

Intermediate Presbyopia (New Wearer): Douglas P. Benoit, OD, FAAO

Background

Patient JP was a 56-year-old insurance adjuster who came into the office for a routine eye examination. She reported a gradual decrease in her near vision but indicated her distance vision was fine. She was interested in contact lenses, but had always been told she was not a candidate due to her astigmatism.

Test Procedures, Fitting/Refitting, Design and Ordering

Manifest Refraction:

OD: -3.75 -1.00 x 175
OS: -4.75 -1.00 x 010
Add: +2.25D

Keratometry:

OD: 42.25 @ 180; 43.50 @ 090
OS: 42.00 @ 180; 43.12 @ 090

This patient was right eye dominant with a palpebral fissure height equal to 11mm. The upper lids overlapped the superior limbus by 1.5mm with the lower lids tangent to the inferior limbus. The pupil diameter was 4.5mm in normal room illumination. She also exhibited some plugged Meibomian glands.

Based upon patient needs and the examination, a segmented/translating GP design was recommended:

Diagnostic Lenses:

Metro Seg (Metro Optics)
Base Curve Radius: OD 8.00mm; OS 8.10mm
Overall Diameter: 9.50mm OU
Power: -3.00D and +2.00D add OU
Seg Height: 1.0mm below geometric center
Prism: Medium prism @ 090

The distance visual acuity was: OD 20/20 with a -0.75D over-refraction; OS 20/20 with -1.25D over-refraction. The near vision was 20/20 OU with +0.50D over the trial lens/distance over-refraction combination.

Each lens positioned centrally, just touching the lower lid after the blink. The movement was 1mm in primary gaze and each lens exhibited good translated on down gaze. There was slight nasal rotation of each lens. The right lens segment was at the lower pupil margin in primary gaze, while the left lens seg line was slightly up into the pupil. With most segmented lens designs this would represent an ideal seg position. The fluorescein pattern exhibited an alignment fit centrally OD and mild apical touch OS. There was good peripheral clearance OU. Based upon these findings, the base curve was changed OS to get the lens to position inferiorly and the resultant power compensation was made. The following lenses were ordered:

Lens Design: Metro Seg (Light Blue Tint, Dot OD)

Base Curve Radius: OD 8.00mm; OS 8.05mm
Overall Diameter: 9.50mm OU
Power: OD -3.75D; OS -4.50D
Add: +2.50D add OU
Seg Height: 1.0mm below geometric center
Prism: Medium prism @ 090

Patient Consultation and Education

Warm compresses to open the Meibomian glands were discussed. The patient was to do these nightly for 5 minutes between the fitting and dispensing visits. At dispensing, the patient noted good comfort after 3-4 minutes of lens wear. The vision was 20/20 at distance and near. Each lens positioned centrally, with the segment at the lower pupil margin OU. There was a slight nasal rotation OU. Movement was 1mm in primary gaze with good translation on down gaze. The patient was instructed on care and insertion and removal was practiced. The need for gradually increasing wear time was discussed. The possible need to change lens parameters was again reviewed.

Follow-Up Care/Final Outcome

At the 1 week progress evaluation, the patient reported good vision for all tasks. Comfort was good for the 11-12 hours per day wearing schedule. The use of supplemental lubricants helped but was not needed very often. The patient reported no spectacle blur after lens removal.

Her vision was 20/20 OD, OS, OU at distance and at near. Position and movement was similar to the dispensing visit. No modification was necessary. This patient has continued to do well.

Discussion/Alternative Management Options

This patient was a great candidate for a GP lens based upon vision and physiology. This patient could have been fit with a simultaneous design, either aspheric or concentric, and distance vision would have been fine, although the near vision may have been somewhat compromised. In the segmented design, if the lens does not translate well, the lens can be truncated. This thickens the lower lens edge making it less likely to slide behind the lower lid on downgaze.

A high riding lens that is interfering with distance vision can be helped by increasing the prism ballast and/or thinning the upper edge, lowering the seg height, decreasing the lens diameter, etc. A soft lens, in either a monovision or bifocal/multifocal configuration could also be used. The initial comfort would be good, but the vision may be less sharp than with a GP lens. Lastly, a single vision lens, soft or GP, could be used with readers over them for near. Most patients do not like this option because spectacle wear is still necessitated.

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