GP Lens Case Grand Rounds Troubleshooting Guide

Young Progressive Moderate Myopic Patient: Annie Chang, OD, FAAO

Background

DK was a 7 year-old female whose mother was quite concerned about her fast progressive myopia. Over a three month period DK’s refraction changed from -2.25DS to -2.75DS. Her mother received education that reverse geometry orthokeratology GP contact lenses, multifocal soft lenses, and atropine drops could help slow further myopic development. DK had not previously worn contact lenses, but her sister had worn orthokeratology contact lenses. The mother elected to pursue reverse geometry orthokeratology GP contact lenses.

Test Procedures, Fitting/Refitting, Design and Ordering

Manifest Refraction and Visual Acuity:

OD -2.50 -0.25 x 174           20/20-
OS -2.50 -0.25 X 180           20/20-

Topography Sim K:

OD: 45.50 @ 180 / 46.63 @ 090      (1.12D with-the-rule astigmatism)
OS: 45.50 @ 179 / 46.50 @ 089      (1.00D with-the-rule astigmatism)

Lens Selection:

The Paragon CRT Slide Ruler was used to determine the initial trial lenses from our fitting set.

Base Curve (BC): The base curve, or treatment curve, is a central 6.0 mm fixed Optic Zone, and it’s the radius of curvature that flattens the cornea to reduce the myopia. It is not used for centration purposes. The BC should be centered over the pupil, and the Refraction Over Lens (ROL) should be plano to +/- 0.50D

Return Zone (RZD): The return zone redirects the lens back toward the cornea starting at the junction with the base curve. 

Landing Zone: The landing zone is the outermost peripheral curve that determines edge lift.

Lens-to-Cornea Fitting Relationship using sodium fluorescein:

OD: central bull’s eye pattern / 4mm treatment zone / average RZD / average PC / good lens movement / centered 

OS: OD: central bull’s eye pattern / 4mm treatment zone / average RZD / average PC / good lens movement / centered

Dispensing:

The patient was not sufficiently proficient with lens removal after application and removal training. The lenses were not dispensed and DK was rescheduled for additional training. 

At the next visit, DK showed proficiency with lens application, removal, and proper lens care. The initial trial lenses were dispensed. She was scheduled to wear the lenses for approximately eight hours overnight and report for a 1-day follow-up visit wearing the lenses.

One-Day Follow-Up Visit:

DK reported mild lens awareness during lens wear (“tickles”). She had worn the lenses for 10 hours at the time of the visit.

Visual acuities with the lenses on were:

OD: 20/20
OS: 20/25

One-Day Visit Lens-to-Cornea Fitting Relationship using sodium fluorescein:

OD: central bull’s eye pattern / 4mm treatment zone / average RZD / average PC / good lens movement / no lens binding or superficial punctate keratitis (SPK) / slight temporal decentration 

OS: central bull’s eye pattern / 4mm treatment zone / average RZD / average PC / good lens movement /  no lens binding or superficial punctate keratitis (SPK) / slight nasal decentration

One-Day Follow-Up Topography:

Centered treatment zone OD and OS 

One-Day Visit Visual Acuities and Manifest Refraction without Contact Lenses:

OD: 20/20-  Unaided
OS: 20/20-  Unaided

Manifest Refraction:

OD: -0.50DS   20/20-
OS: -0.50DS   20/20-

One-Day Visit Plan:

Continue overnight wear (~8 hours) and return for one-week follow-up visit after lens removal. 

One-Week Follow-Up Visit:

DK reported “good” unaided vision at distance and near. Lenses were worn every night since the last visit; 11 hours the previous night. DK reported no lens awareness OD and mild lens awareness OS. No reported redness, irritation, or glare. Unaided distance visual acuities were: OD: 20/20++ and OS: 20/20- -.  

One-Week Manifest Refraction:

OD: +0.25 -0.25 X 150      20/15
OS: -0.25DS     20/15-

One-Week Visit Lens-to-Cornea Fitting Relationship using sodium fluorescein:

OD: central bull’s eye pattern / 4mm treatment zone / average RZD / average PC / good lens movement / no lens binding or superficial punctate keratitis (SPK) / centered 

OS: central bull’s eye pattern / 4mm treatment zone / average RZD / average PC / good lens movement / no lens binding or superficial punctate keratitis (SPK) / centered

One-Week Follow-Up Topography:

Centered treatment zone OD and OS 

One-Week Visit Plan:

Continue with initial lenses: 

Continue overnight wear (~8 hours) and return for one month follow-up visit. 

One-Month and One-Year Follow-Up Visits:

DK reported good unaided vision at both the one month and one year follow-up visits. At one month visit the uncorrected visual acuities were OD and OS: 20/20-; at one year the VA’s were OD and OS: 20/15-. Topography revealed a centered treatment zone in each eye. The patient was scheduled to return in one year. 

Discussion/Alternative Management Options

Overnight orthokeratology using a reverse geometry corneal GP lens design was approved by the US Food and Drug Administration (FDA) in 2002. At that time, it was approved for up to -6D of myopia and -1.75D of astigmatism correction.

If a patient presents with severe myopia, one option is to correct as much myopia as you can safely with overnight orthokeratology and then prescribe glasses or soft contact lenses for the patient to see clearly during the day. There have been some reports that this could also serve to control myopia from increasing.  Smaller treatment zones have also been used to decrease larger amounts of myopia with overnight orthokeratology. Toric peripheral curves have been prescribed to improve treatment centration for patients with toric corneas and refractive astigmatism. Hyperopia and presbyopia can be corrected with overnight orthokeratology by flattening the paracentral portion of the cornea. This may cause an increase in corneal aberrations and halos. (Williams 2016)

References

Williams BT. Orthokeratology for hyperopia and presbyopia. Contact Lens Spectrum 2016;31(8):34-39,55.

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