Soft Toric Lens Failure – Poor Vision: Phyllis Rakow, COMT, FCLSA
Background
RG, a 44 year old female, presented with a history of poor vision with soft spherical and toric contact lenses over a 14 year period. She had tried four different soft toric designs prior to her visit, but was unable to achieve rotational stability with any of them. Also, her current soft toric lenses were not silicone hydrogels.
Manifest Refraction:
OD -3.00 -1.50 X 105 20/25+
OS -3.50 -2.50 X 090 20/20-
Keratometry Readings:
OD 46.37 @ 155/47.00 @ 065
OS 45.87 @ 090/46.37 @ 180
Original keratometry readings from 14 years previous were:
OD 44.75/45.00 (no axis indicated)
OS 44.75/45.25 (no axis indicated)
Slit Lamp Examination:
Neovascularization inferonasally OU; no visible corneal edema, but hypoxia due to lens overwear of non-silicone hydrogel lenses suspected.
Patient Consultation and Education
This patient was advised to discontinue soft lens wear and return for a corneal GP fitting in two weeks. RG was told that the steepness of her corneas precluded successful soft toric fitting with stable visual acuity at this point in time. RG also noted that the quality and consistency of her vision was not as optimal as her spectacle vision. Advantages of GP lens wear, especially the increased oxygen transmission compared to her current non-silicone hydrogel lenses and better visual acuity were discussed. RG decided to be fit with corneal GP contact lenses. At the fitting visit, new keratometry readings and manifest refraction were performed. Residual astigmatism and the need for a special front surface toric GP design for the left eye were explained to the patient.
Manifest Refraction:
OD -3.00 -0.75 X 105
OS -2.25 -1.50 X 090
Keratometry:
OD 45.37 @ 175/46.12 @ 085
OS 45.37 @ 090/45.62 @ 180
Lenses Ordered:
| BCR (mm) | Power (D) | OAD (mm) | Material Dk | |
| OD | 7.50 | -2.75 | 9.6 | 65 |
| OS | 7.55 | -2.00 -1.00 X 90 | 9.6 | 65 |
Dispensing Visit
Visual Acuity:
OD 20/20 with effort
OS 20/20
Slit Lamp Examination:
Lid attachment and alignment with fluorescein OU
Follow-Up Care/Final Outcome
The lenses were dispensed with the Boston Advance cleaner and the Boston Original Conditioning solution. RG adapted rapidly and appreciated the consistently crisp vision with her new GPs. Initially, she still had enough accommodation to read with her contact lenses, but over time, she purchased drugstore reading glasses. Three years after her corneal GP refit, we suggested trying multifocal GPs.
Manifest Refraction:
OD -2.50 -1.25 X 95
OS -1.75 -0.25 X 88
Add +1.75 OU
Keratometry Readings:
OD: 45.25@90º/45.62@180º
OS: 45.62 DS
RG was fit with Art Optical Magniclear Plus front surface multifocals. These lenses combine the principle of simultaneous vision for distance and intermediate with that of translation for near vision. They have a low negative eccentricity, 7.0 mm distance zone, and a spherical near zone that is controlled independently of the distance/intermediate zones with no image jump.
Often patients require a significantly greater add power with these lenses than they have in their spectacles.
Lenses Ordered for RG:
Magniclear Plus
| BCR (mm) | Power (D) | OAD (mm) | Add (D) | Material Dk | |
| OD | 7.50 | -2.25 | 9.5 | +3.75 | 65 |
| OS | 7.50 | -2.50 | 9.5 | +3.75 | 65 |
Discussion, Alternative Management Options
Some fitters hesitate to recommend GP lenses to adults because they think they will not be able to adapt to a GP material at this point in life. Placing a diagnostic GP lens on astigmatic patients’ eyes will often achieve a “WOW” factor when they realize how sharp and stable their vision is.
A multitude of excellent GP multifocal lenses are available in anterior and posterior surface designs. Some of the posterior surface designs allow fitters to incorporate an additional concentric zone of add power on the anterior surface of the lenses for mature presbyopes. As most patients today spend time at a computer, this fitter prefers using an aspheric multifocal GP to an alternating vision bifocal design whenever possible.
We explain to our patients that their entire multifocal prescription is compressed into less than 9.5 mm of space, including the bevels, and that they might occasionally need to use a pair of low-power “booster glasses” to see very tiny print. Surprisingly few GP wearers actually need this supplementary power; however, it does emphasize that patients need to have realistic expectations about presbyopic contact lens correction.
Recently, multifocal scleral GP contact lenses reached the marketplace. Also, today’s multifocal soft contact lenses are a viable option for presbyopic patients with less than one diopter of refractive astigmatism. They are available in daily and monthly replacement options. Soft lenses are also now available that correct both astigmatism (toric) and presbyopia (multifocal) patient needs.
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