Refractive surgery techniques such as photorefractive keratectomy (also known as PRK surgery) have come a long way. However, even with the introduction of novel laser eye surgery methods such as SMILE surgery, there still remains several eligibility criteria to ensure the procedure is safe and effective. Because of this, you may find yourself unsuitable for certain types of laser eye surgery operations due to thin corneas. Keep reading to learn about your options for refractive surgery and thin cornea treatment.
How Does Refractive Surgery Work?
Refractive surgery is a type of eye operation that aims to surgically correct the eye’s refractive error, which is commonly referred to as your prescription. Many refractive surgery techniques utilise a medical laser to achieve this, though not all methods depend on a laser tool. Laser eye surgery techniques include LASIK (laser assisted in situ keratomileusis), PRK surgery (photorefractive keratectomy), and SMILE (small incision lenticule extraction).
Laser eye surgery works by adjusting the shape of the cornea, the transparent tissue at the front of the eyeball. By modifying the curvature of this structure, light is directed into a sharp focus as it passes into the eye, providing clear vision. An excimer laser is used to vaporise selected areas of the cornea in a process known as photoablation. Because of this, a minimum amount of corneal thickness is required to ensure that post-operatively, the structural integrity of the cornea is not compromised. With a thin cornea, treatment options become more limited.
The amount of corneal tissue required for vaporisation is guided by your prescription. Higher prescriptions will need to have more tissue removed to achieve clear, spectacle-free vision. In addition to ruling out an overly thin cornea, treatment eligibility is also guided by other factors such as your prescription, the presence of any corneal conditions or abnormalities, and even your hobbies or vocation.
Thin Cornea Treatment Options
Certain refractive surgery techniques are more suited to thin corneas compared to others. A comprehensive pre-operative examination with your ophthalmologist will determine which type of procedure is the best for you.
PRK surgery
When it comes to laser eye surgery techniques, PRK surgery is more favoured over LASIK in the situation of thin corneas. The reason behind this is because LASIK involves the formation of a flap of corneal tissue, which includes the superficial epithelial layers as well as some deeper stromal tissue. This flap is moved to the side and then later repositioned after the excimer laser has performed photoablation on the corneal stroma. Because of this flap, less stromal tissue is available for photoablation. However, the photorefractive keratectomy technique does not involve the formation of a flap of corneal tissue. Instead, only the epithelium is removed in a process called debridement. This is performed either with a chemical solution or with a manual tool. The epithelium then regenerates during the healing period after surgery. Debridement allows access to the underlying stromal tissues for the excimer laser without reducing the available corneal thickness, making photorefractive keratectomy more suitable for thin corneas.
LASEK surgery
LASEK is a technique that sits between the LASIK and PRK methods, combining the best of both techniques. It stands for laser epithelial keratomileusis. During LASEK, the epithelium is loosened and carefully removed from the eye. However, instead of being discarded as in PRK, it is later replaced once the photoablation step is complete, similar to repositioning the corneal flap in LASIK. This makes LASEK suitable for those who are after a shorter recovery time than offered with traditional PRK, but who also wish to avoid the risk of flap-related complications that come with LASIK.
In some situations, an individual may have such thin corneas that it excludes them from any sort of laser eye surgery technique, including PRK. Fortunately, refractive surgery options still exist for those with particularly thin corneas.
ICL surgery
An implantable Collamer lens (ICL) is a good option for those with thin corneas as there is no corneal tissue removed during the procedure. The only disruption to the cornea during the ICL procedure is a small incision through which the ICL is inserted. Similar to a contact lens, an ICL is an implant that’s designed to correct your eye’s prescription. It’s surgically inserted between the coloured iris and the natural lens of your eye.
Unlike refractive lens exchange (RLE), leaving the eye’s natural lens in place means you can retain your natural focusing ability, a process called accommodation. As accommodative ability naturally declines with age, ICL surgery is suitable for individuals who still have a functional degree of accommodation, typically those aged under 50 or 60 years old.
RLE surgery
Refractive lens exchange (RLE) is similar to a cataract operation. During the RLE procedure, the natural lens of the eye is surgically removed and an artificial lens implant is put in its place. This implant, called an intraocular lens, is calculated to correct your eye’s prescription. RLE is suitable for individuals whose thin corneas exclude them from other laser eye surgery techniques, and who no longer have any useful accommodation. The main disturbance to the cornea during the RLE procedure is when an incision is created to insert the lens implant though there may be some minor disruption as the eye’s natural lens is fragmented and removed.
Although thin corneas do present more of a challenge when it comes to refractive surgery, there are still options available to you. If you’re interested in surgical correction for your vision, speak to your ophthalmologist by calling on 03 9000 0389. about what may be the safest and most effective technique for you.
Note: Any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner.
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