Eyeworld

42 | EYEWORLD | FALL 2025 R EFRACTIVE and the irregular astigmatism that is present. "I even prefer in these cases videokeratography; that is a topography system that's based on ker- atoscopy or the video image of the Placido disc. Looking at the Placido image itself allows you to see the general axis and magnitude of the astigmatism over the entrance pupil." He added that you can also use optical aberrometry, which will define the most important aberrations of the cornea. Thus, inferring the astigmatism from the corneal topography analysis is often a good starting point. If the patient has old glasses, Dr. Hersh said you can start with that. But often old glasses don't bear a resemblance to what their actual refraction should be because when they're look- ing out of the cornea, they are looking through multiple refractive spots, and each spot is focus- ing light in a different location. Using topogra- phy is a good starting point for the refractive cylinder, and having them choose among a wide range of spheres, often starting with 3 diopter increments, along with this is also a good start- ing point for the spherical correction; refining from that gives the best results. Another important factor, Dr. Hersh said, is pupil size. In a pristine cornea, pupil size doesn't make a difference because it's always a similar sphere and cylinder, but as the pu- pil size changes in keratoconus, the type and magnitude of aberrations can change. That can change subjective refraction in dark and light. "I think it is advantageous to do refraction in both photopic and scotopic conditions," he said. Then you might take into account what the patient is doing most or give two pairs of spectacle correc- tion, one for daytime and one for night driving. As far as correction non-surgically, the mainstay is contact lenses, Dr. Meghpara said. Patients are always going to see better in contacts compared to glasses because you can treat higher amounts of refractive error with a contact lens. Options depend on the severity of ker- atoconus the patient has and how irregular the cornea is. "If it's a milder form where the astigmatism is regular and you put them in the phoropter and can refract them pretty well, often these patients will do well in a soft contact lens, or there are special contacts that are soft but meant for keratoconus patients," he said. "The progression beyond that goes to typical RGP lenses." Dr. Meghpara said these are often smaller in diameter, and to try to get them to fit on a steep, protruding cornea is difficult, so wider diameter contact lenses are typically what he's using. These could be hybrid lenses that are soft on the outside and hard in the middle. However, if you're not careful with the fit, Dr. Meghpara said patients can run into issues with lenses that are fit too tightly, and they can get corneal surface issues, signs of contact lens overwear, or neovascularization of the cornea. "The gold standard now is the scleral con- tact lens," Dr. Meghpara said, adding that there are many options. There are regular scleral lens- es, customized scleral lenses, and PROSE lenses. "One of our optometrists is using EyePrintPRO [EyePrint Prosthetics]," he added. This involves taking a mold of the eye and using a custom- ized process to get a contact that mimics the surface of the patient's eye. "I think the revolu- tion in contact lenses has reduced the amount of corneal transplants that I'm having to do for keratoconus." If a keratoconus patient wants or needs surgery, Dr. Meghpara said there aren't many refractive options. The problem is having kera- toconus is a contraindication to having corneal refractive surgery, whether it's LASIK, PRK, or SMILE, because the risk of ectasia is high. "You need to think outside the box when it comes to surgical options for these patients. They're going to be younger so not necessarily cataract age," he said. Outside the U.S., there is a treatment algo- rithm where patients will get crosslinked first to strengthen the cornea to potentially make them a candidate for corneal refractive surgery, then possibly do PRK on top of that to reduce risk of ectasia. Dr. Meghpara said this may be catching on in the U.S., but outcomes are still unpredict- able, and the risk of haze in the cornea after that is high. "If someone with keratoconus comes in interested in refractive surgery, I'm usually doing ICL surgery [STAAR Surgical], and it's a different mindset and counseling for that," he said. The expectation with refractive surgery is to see great without glasses or contacts. "When it comes to keratoconus patients, we have to tell them it's unlikely they'll be perfect, and make sure to tell them that vision will likely be better in refractive contact lenses compared to with refractive surgery. Our goal is to debulk that continued from page 41 continued on page 44

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