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RK Fluctuations and Hyperopia (Farsighted) Shift

Years after Radial Keratotomy, some patients experience fluctuations in vision and are becoming hyperopic.

Close up image of eye.  
A shift to farsighted vision after RK can provide poor vision when combined with presbyopia.  

Many individuals who had Radial Keratotomy (RK) years ago are now experiencing fluctuation in vision quality throughout the day and a shift in visual acuity toward hyperopia (farsighted, longsighted) vision. Some of this shift may be natural.

Natural Hyperopic Shift

Many people become more hyperopic in the fifth and sixth decade of life.  The natural hyperopic shift may not explain all of the phenomena of hyperopia after RK, however the natural changes of the eye it may be responsible for some.

RK Corneal Weakening

The process of RK is to make four, eight, twelve, or more radial incisions through about 90% of the cornea. These incisions weaken the cornea, causing a flattening of the center of the cornea and reducing myopic (nearsighted, shortsighted) vision. The healing of the RK incisions restores some of the cornea's strength and provides stability. Unfortunately for some, the RK incisions did not provide enough strength to the cornea for the long term.

Daily Fluctuations and Hyperopic Shift

Because some corneas with previous RK have become unstable, patients experience fluctuations in visual acuity throughout the day. The internal pressure of the eye pushes out on the cornea, causing a central steepening and creating hyperopia. Fluctuations and hyperopic shift does not occur to everyone who had RK. There appears to be some correlation between the number of radial incisions and the probability of corneal instability. Those who had more incisions tend to be more likely to develop unstable corneas, however instability or stability can occur with few or multiple incisions. Every individual is different.

Presbyopia and Hyperopia Equal Poor Vision Quality

Presbyopia is when the natural crystalline lens of the eye is less able to change shape to focus on objects near. Presbyopia usually becomes problematic at about age 40. The combination of hyperopia and presbyopia often provides poor quality vision at all distances. The obvious answer to this problem is to correct the hyperopia and use reading glasses or bifocals for near vision.

Hyperopic vision can be vastly improved with glasses, but due to the physics of hyperopic correction, much better correction may be achieved with contact lenses. New contact lens materials that allow more air to pass through the lens make contact lens wear much more comfortable than before. A scleral contact lens can sit over the cornea, needing to touch only the outer white part of the eye. New technology rigid gas permeable (RGP) contacts are much more comfortable than those in the past. An advantage of an RGP lens is that it can add stability to a fluctuating cornea.

Surgical Possibilities

Many former RK patients are appropriate candidates for conventional or custom wavefront Lasik, Bladeless Lasik, PRK, or LASEK. If the patient is fully presbyopic, an alternative that may be appropriate is Refractive Lens Exchange (RLE). RLE is the same as cataract surgery. The natural lens is removed and replaced with an artificial lens that is calculated to correct the hyperopia. If the cornea is stable, RLE may be an appropriate method to resolve hyperopia.

Every eye that has had previously surgery is unique. Whether or not a surgical correction is appropriate will depend upon each person's individual circumstances. Only a comprehensive evaluation by a competent doctor will be able to determine what is best.

Developing Technology

A very interesting technique that is in the early stages of development and availability is Corneal Collagen Crosslinking with Riboflavin (CxL). This is a process of applying light to the cornea while it is protected with vitamin enriched eye drops to cause the cornea to become stronger and more stable.

Looking For Best Lasik Surgeon?

If you are ready to choose a doctor to be evaluated for conventional or custom wavefront Lasik, Bladeless Lasik, PRK, or any refractive surgery procedure, we recommend you consider a doctor who has been evaluated and certified by the USAEyes nonprofit organization. Locate a USAEyes Evaluated & Certified Lasik Doctor.

Personalized Answers

If this article did not fully answer your questions, use our free Ask Lasik Expert patient forum.

Recent RK Medical Journal Articles...

Related Articles

Femtosecond-assisted laser in situ keratomileusis for consecutive hyperopia after radial keratotomy.

J Cataract Refract Surg. 2015 Aug;41(8):1594-601

Authors: Leccisotti A, Fields SV

PURPOSE: To evaluate femtosecond-assisted laser in situ keratomileusis (LASIK) for the treatment of hyperopic shift after radial keratotomy (RK).
SETTING: Private practice, Siena, Italy.
DESIGN: Prospective case series.
METHODS: Eyes with a spherical equivalent (SE) of +1.0 diopters (D) to +4.0 D after RK with 6 or 8 incisions had LASIK. The flap (nominal thickness 130 μm) was created with a femtosecond laser (LDV Z2); the refractive ablation was performed with an excimer laser (217P). The flap was dissected in a centrifugal fashion along previous RK cuts.
RESULTS: Eighteen eyes of 10 patients were treated. Preoperatively, the mean defocus equivalent was 3.13 diopters (D) ± 0.71 (SD); the corrected distance visual acuity (CDVA) was 0.09 ± 0.06 logMAR. At 9 months, the mean defocus equivalent was 0.51 ± 0.47 D (P < .05), with 13 eyes (72%) having 0.50 D or less of defocus equivalent and 16 eyes (89%) having 1.0 D or less of defocus equivalent. The mean CDVA was 0.04 ± 0.06 logMAR (P < .05). No lines of logMAR CDVA were lost. The mean uncorrected distance visual acuity was 0.11 ± 0.10 logMAR. The safety index was 1.11; the efficacy index was 0.97. No retreatments were performed. Flap complications were limited to an RK incision opening larger than 2 mm in 3 eyes and 1 case of a small, self-limiting epithelial ingrowth.
CONCLUSION: Laser in situ keratomileusis with a low-energy femtosecond laser was a safe and effective approach to treat post-RK hyperopia, causing no relevant inflammation.
FINANCIAL DISCLOSURE: Neither author has a financial or proprietary interest in any material or method mentioned.

PMID: 26432115 [PubMed - in process]


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