Cataract Treatment Interventions

Cataract Treatments

Pre-operative considerations: Patients with pre-existing proliferative diabetes-related retinopathy are more likely to progress rapidly after cataract surgery, therefore panretinal photocoagulation (PRP) is recommended preoperatively. Macular edema should be adequately treated prior to surgery because pre-existing maculopathy may aggravate postoperatively and is strongly associated with a poor visual outcome 13.

Anti-cataract treatment: While maintaining good glucose, lipid and blood pressure control, may delay the onset of cataract, additional supplements have shown promise pre-clinically. 

Aldose reductase inhibitors(ARIs): Pre-clinical studies have shown that ARIs can delay diabetes induced cataract in animal models. Certain non-steroidal anti-inflammatory drugs (NSAIDs), acting through an ARI mechanism such as sulindac, aspirin, or naproxen have been reported to delay cataract in diabetic rats11.

Antioxidants: As oxidative damage occurs indirectly as a result of polyol accumulation during diabetes-related cataract formation, the use of antioxidant agents may be beneficial. A number of different antioxidants have been reported to delay cataract formation in animals with diabetes. These include the antioxidant alpha lipoic acid, vitamin E and pyruvate11.

Cataract Surgery and Intravitreal Injections: Intravitreal steroids may be considered during cataract surgery in the eyes with DME without epiretinal membrane or tractional component, particularly if the patient has not been treated previously. Coexistent centre-involving DME at the time of cataract surgery warrants combined phacoemulsification and anti-VEGF injections as treatment for the DME simultaneously. 

Combined cataract surgery and vitrectomy: Patients living with diabetes undergoing vitrectomy often have coexisting cataracts. Furthermore, lens opacities often progress following vitrectomy. Careful patient selection and combining the two procedures can offer more rapid visual rehabilitation, avoid a second operation, and simplify surgical interventions in patients who are likely to require multiple procedures.

Types of Cataract Surgery

Extracapsular Cataract Extraction is a method of cataract surgery that involves removing the eye’s natural lenses while leaving the back of the capsule that holds the lens in place. This procedure requires a much smaller incision than the older process called Intracapsular Cataract Extraction in which the lens and the entire capsule were removed, which was associated with difficulties in lens replacement.

Phacoemulsification (Phaco) is more modern technique which is associated with better visual results, less inflammation and less need for capsulotomy (Capsulotomy is a type of eye surgery in which an incision is made into the capsule of the crystalline lens of the eye, thus providing a clear path for light to reach the retina thus reducing the opacity of the lens of the eye.) as compared to extracapsular cataract surgery. During phacoemulsification, a surgeon makes a small incision at the edge of the cornea and then creates an opening in the membrane that surrounds the lens. A small ultrasonic probe is then inserted, breaking up the cloudy lens into tiny fragments. The instrument vibrates at ultrasonic speed to chop and almost dissolve the lens material into tiny fragments. The fragments are then suctioned out of the capsule by an attachment on the probe tip. After the lens particles are removed, an intraocular lens implant, commonly referred to as an IOL, is implanted and positioned into the lenses natural capsule.

The IOL is inserted through the tiny corneal incision through a hollowed out tube. Once the lens is pushed through, it unfolds and is positioned in place. 

Phacoemulsification is typically performed in an outpatient surgery centre and normally does not require a hospital stay. The cataract surgery procedure is performed under local anaesthesia (an aesthetic injected around the eye) or topical anaesthesia (numbing drops inserted into the eye).

Phaco Surgery Recovery: The incision made in the cornea usually requires no stitches and is self-sealing. Within a few days, the incision heals completely. Post-operative eye drops are prescribed and usually consist of antibiotics, steroids, and a non-steroidal anti-inflammatory medication. These drops reduce inflammation and prevent infection. The antibiotic is usually discontinued within 7-10 days. The steroid and non-steroidal anti-inflammatory are taped over 3-6 weeks depending on the surgery. Most patients have vision improvement almost immediately and vision tends to steadily improve over 4-5 weeks.

Cataract Surgery Risks

Cataract surgery may also be referred to as lens replacement surgery, and as the name suggests involves the removal of the natural lens and replacement with an artificial one. Cataract surgery is performed by an ophthalmologist. Cataract surgery is advisable prior to lens opacity precluding detailed fundus examination. Phacoemulsification is the preferred surgical technique. 

Cataract surgery is more complicated in patients with diabetes overall. The basement membrane of the lens (or lens capsule) is known to be thicker in patients with diabetes, which is similar to the thickened vascular basement membrane in these subjects. This thickened capsule is more easily crumbled and accidental rupture during lens extraction (cataract surgery) seems to be more common in patients with diabetes. Lens capsule changes may also affect performing capsulorrhexis  (removal the capsule of the lens from the eye during cataract surgery by shear and stretch forces) during phacoemulsification13 .

Patients with diabetes have a higher risk of complications after cataract surgery compared to nondiabetics.

Intra Ocular Lenses

Monofocal IOL: This is the most common. Unlike your natural lens, which can stretch or bend to help your eye focus, this implant stays focused at one fixed distance. If yours focuses at a distance, you might be able to see things far away but need glasses to read or see close up.

Multifocal implant: Like glasses with bifocal or progressive lenses, this lens has areas that help you see things at different distances. It could take several months for your brain to adapt so your vision seems natural.

Accommodating IOL: This flexible option acts more like your natural lens and focuses at more than one distance. It makes you less likely to need reading glasses.

Toric IOL: You’ll get this is if you have astigmatism, or a cornea that’s more rugby ball-shaped than round. This can make vision blurry all over, not just close up or far away. This lens lessens astigmatism so you won’t need glasses to correct it after your surgery.

 

Large diameter IOLs are preferred to facilitate visualisation and treatment of the peripheral retina in Diabetic Retinopathy.

Corneal hypoesthesia (numbness) is common in diabetic patients. Special care should be taken to protect the corneal epithelium during surgery. Corneal abrasions during or after surgery may be slow to heal and lead to recurrent corneal injury. Small-incision surgery can minimise further decrease in corneal sensation. Due to corneal hypoesthesia and the increased risk of infection, patients with diabetes are poor candidates for long-term aphakic (without natural lens) contact lens wear. Thus a posterior chamber intraocular lens (IOL) should be inserted when possible.

With modern minimally invasive cataract operations most studies agree that the risk of enhanced post op Diabetic Retinopathy progression after cataract surgery is small in patients without severe Non Proliferative Diabetic Retinopathy (NPDR)or preexisting Diabetic Macular Edema (DME) 11. Poor visual outcomes are related to poor metabolic control rather than cataract surgery in these cases.

In eyes where there is pre-existing DR there is an increased risk of DME, or progression of existing DME in the post-operative period and Best Corrected Visual Acuity (BCVA) gains are limited without further intervention. Anti VEGF therapy at the time of surgery is advocated.

Surgery may cause a rapid acceleration of retinopathy, induce rubeosis (growth of blood vessels on the iris) or lead to macular changes, such as macular edema or cystoid macular edema. The worst outcomes may occur in operated eyes with active proliferative retinopathy and/or pre-existing macular edema 11.

Timing of cataract surgery has shifted in recent years to that of choosing to have cataract surgery earlier rather than later and this has contributed to improved visual outcomes.

 

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