Ophthalmic surgery is a highly specialized field dedicated to treating conditions affecting the eye and its surrounding structures. Technological advancements have transformed this field, moving from invasive techniques to microsurgery and laser-assisted procedures. Modern ophthalmic surgery offers interventions ranging from elective vision correction to sight-saving procedures for diseases like glaucoma and retinal detachment. Procedures are typically classified by the part of the eye being treated, allowing surgeons to target specific anatomical and pathological issues with precision.
Refractive Surgeries for Vision Correction
Refractive surgery aims to reshape the eye’s focusing elements, primarily the cornea, to reduce or eliminate the reliance on glasses or contact lenses. The two most common methods are Laser-Assisted In Situ Keratomileusis (LASIK) and Photorefractive Keratectomy (PRK), both using an excimer laser to ablate microscopic amounts of corneal tissue. LASIK involves creating a thin, hinged flap on the cornea’s surface, which is lifted to allow the laser to reshape the underlying stromal tissue. The repositioned flap acts as a natural bandage, facilitating rapid recovery and quick vision improvement.
PRK is a surface ablation procedure involving the gentle removal of the cornea’s outermost layer, the epithelium, before applying the excimer laser directly to the stroma. The epithelial layer must regenerate over several days, leading to a longer and more uncomfortable recovery period than LASIK. However, PRK avoids the risks associated with creating a corneal flap and is often recommended for patients with thinner corneas or those involved in high-contact activities.
For individuals who are not candidates for laser-based corneal reshaping, such as those with severe prescriptions or thin corneas, Implantable Collamer Lenses (ICLs) offer an effective alternative. These phakic intraocular lenses are surgically placed inside the eye, typically between the iris and the natural lens, without removing the eye’s natural lens. ICLs are made of a soft, biocompatible material and function like an internal contact lens, offering high-quality vision correction while remaining removable if necessary.
Treatments Involving the Ocular Lens
The most frequently performed eye surgery globally is cataract removal, a procedure necessary when the natural lens becomes cloudy and opaque, interfering with light passage to the retina. The standard technique is phacoemulsification, which uses high-frequency ultrasound energy to break the cloudy lens into small fragments. These fragments are then removed through a small incision, typically less than three millimeters, using an aspiration and irrigation system.
Once the natural lens is removed, it is replaced with an artificial Intraocular Lens (IOL), which is folded and inserted through the same incision into the lens capsule. The choice of IOL significantly influences the patient’s vision after surgery. Monofocal IOLs are the standard option, providing clear vision at a single, predetermined distance, usually far vision, meaning the patient will still need glasses for reading or intermediate tasks.
Premium IOLs offer a wider range of visual correction. Multifocal IOLs use advanced optics to split light, creating multiple focal points to provide functional vision at distance, intermediate, and near ranges, potentially minimizing the need for glasses. Toric IOLs are designed specifically to correct astigmatism, a refractive error caused by an irregularly shaped cornea or lens.
Surgical Management of Glaucoma and Ocular Pressure
Glaucoma surgery focuses on lowering the intraocular pressure (IOP) that can damage the optic nerve, often by improving the drainage of aqueous humor. The traditional surgical approach for advanced glaucoma is trabeculectomy, a filtering procedure that creates a small opening in the sclera to form a new drainage pathway. This procedure allows the aqueous humor to bypass the eye’s natural drainage system and collect in a filtering bleb under the conjunctiva.
Trabeculectomy remains the most effective method for achieving very low IOP targets, necessary for advanced or severe glaucoma cases. However, it carries a higher risk of complications and a longer post-operative recovery due to the external filtering bleb. Therefore, it is typically reserved for patients whose condition is not adequately managed by medication or less invasive procedures.
Minimally Invasive Glaucoma Surgery (MIGS) procedures have gained prominence, often used with cataract surgery for patients with mild to moderate glaucoma. MIGS utilizes tiny devices, such as micro-stents or shunts, implanted internally to bypass resistance in the natural drainage system, like the trabecular meshwork. These procedures are simpler, result in less trauma, and offer a quicker recovery with fewer serious complications than trabeculectomy, though they achieve less pressure reduction.
Procedures Addressing the Cornea and Posterior Segment
The cornea, the clear front surface of the eye, can be affected by diseases or trauma requiring tissue replacement, known as keratoplasty or corneal transplantation. Penetrating Keratoplasty (PKP) is a full-thickness transplant where a circular section of the damaged cornea is removed and replaced with a corresponding donor graft, secured with fine sutures. PKP is indicated for deep scarring or conditions affecting all layers of the cornea.
Advancements have led to partial-thickness transplants, which only replace the diseased layers. Endothelial Keratoplasty (EK) procedures, such as DSEK and DMEK, target conditions where only the innermost layer (the endothelium) is dysfunctional, like Fuchs’ dystrophy. These procedures involve removing the diseased endothelium and replacing it with a thin donor layer, leaving the majority of the cornea intact. This results in faster visual recovery and a lower risk of rejection compared to PKP.
Surgery on the posterior segment of the eye, which includes the retina and the vitreous humor, is complex and addresses sight-threatening conditions. Vitrectomy is a microsurgical procedure that removes the vitreous gel, which can become cloudy due to bleeding or contain scar tissue. Removing the vitreous allows the surgeon to access the retina to perform repairs, such as peeling scar tissue causing tractional retinal detachment or clearing blood from a vitreous hemorrhage seen in diabetic retinopathy.
Another common posterior segment procedure is scleral buckling, used to treat rhegmatogenous retinal detachment, where a tear allows fluid to pass underneath the retina. During this surgery, a flexible silicone band, or buckle, is secured to the sclera (the outer white wall of the eye). This band gently pushes the eye wall inward, supporting the retina and bringing the detached layers back into contact, allowing the retina to reattach and heal.