**2. Development of cataract**

Cataract formation or progression is one of the most frequent complications we can find after vitreoretinal surgery. According to several studies, up to 65–80% of the eyes develop a cataract in the 24 months following vitrectomy. [1–6]

Although posterior subcapsular and cortical cataracts can be formed after surgery especially in young patients, nuclear cataracts are much more frequent. Transient subcapsular opacification in the early postoperative period is not unusual. The time interval between vitrectomy and phacoemulsification can vary between 9 and 29 months. [1–3, 7–12]

Even though the exact etiology of cataracts formed after vitrectomy is not known, there are several elements that seem to have a role in it as predisposing or precipitating factors:


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*Cataract Surgery in Post-Vitrectomized Eyes DOI: http://dx.doi.org/10.5772/intechopen.95467*

cells. [1, 2, 8]

cataracts is also lower. [1, 2, 6, 17, 21, 22]

**3. Considerations before cataract surgery**

lens touch in the posterior capsule must be ruled out. [20]

• Vitreous gel removal: the elimination of the vitreous seems to increase the level of retrolental oxygen, generating oxidation of the lens proteins. The incidence of cataracts is much higher after an extensive removal of the vitreous gel and it drops significantly when a limited vitrectomy or a nonvitrectomizing technique is performed. In other surgical procedures that do not include vitrectomy, such a scleral buckling or pneumatic retinopexy, the risk of inducing

• Vitreous substitutes: the presence of gas bubble (SF6 or C3F8) or silicone oil in the vitreous chamber raise the incidence of lens opacification when compared with eyes without any tamponade after surgery. Long lasting substances increase even more the cataract progression. Lens opacity in patients with silicone oil is associated with epithelial cell metaplasia due to inhibition of lens metabolism (anaerobic glycolysis). Secondary gas-related lens opacities can appear as posterior subcapsular vacuoles, which sometimes can be transient and disappear if a layer of liquid is maintained between the gas bubble and the posterior surface of the lens. It is important for the patient to keep the head in a prone position, to prevent the meniscus of the gas bubble from contacting the posterior surface of the lens, and to avoid metabolic disruption of the lens

• Small gauge vitrectomy: although theoretically one of the advantages of the minimally invasive vitreo retinal surgery (23, 25 or 27 gauge) was the lower incidence of cataracts following the operation, there are no studies that demonstrate this relationship. No significant differences have been found between the different systems in the rate of cataract development. It seems that the progression of the lens opacification depends more on the amount of vitreous gel removed rather than the size of the instruments that are used. [1, 23–25]

The surgical criteria should be early, avoiding advanced cataracts requiring higher ultrasound power or poor posterior pole exploration. The final visual acuity after retinal surgery and the underlying retinal pathology for which vitrectomy was required to predict the visual prognosis of the patient should be identified through the anamnesis: retinal detachment with or without macular involvement, proliferative diabetic retinopathy with or without macular edema, history of ocular trauma or high myopia, among others. At times, it is difficult to determine whether the degree of visual impairment in the patient is due to underlying retinal pathology or to cataract progression. In patients operated on for macular disease who present metamorphopsia or central scotoma, these symptoms will persist after cataract surgery. Likewise, it is important to identify the time interval between vitrectomy and cataract, since when opacity occurs at intervals of less than 4 months, iatrogenic

In the ophthalmological examination, pupillary dilation should be evaluated, as in uveitic or diabetic eyes, and the state of the zonular fibers, since there may be phacoiridodonesis due to alteration of the zonule in vitrectomized eyes. It is important to perform a fundus examination to rule out retinal pathology and, occasionally, to perform an optical coherence tomography (OCT) to assess the status of the macula. In patients with macular edema, the need to treat it with an intravitreal injection before surgery or during the procedure itself will be assessed. In the case of not being able to visualize the fundus, an ocular ultrasound should be performed

**Figure 1.** *Development of a nuclear cataract in a diabetic patient after six months of vitrectomy.*

#### *Cataract Surgery in Post-Vitrectomized Eyes DOI: http://dx.doi.org/10.5772/intechopen.95467*

*Current Cataract Surgical Techniques*

favors its progression. [1, 2, 8, 13–15]

erative period. [2, 15–17]

(**Figure 1**). [18, 19]

precipitating factors:

Even though the exact etiology of cataracts formed after vitrectomy is not known, there are several elements that seem to have a role in it as predisposing or

• Age: patients over 50 years of age show a significant increase in cataract

incidence after retinal surgery when compared to younger ones. They usually develop a nuclear sclerosis, whereas posterior subcapsular opacification is more usual at earlier ages. Whenever there is a previous cataract, vitrectomy

• Composition of fluid infusion into the vitreous cavity: the high concentration of 150 mmHg of oxygen in the irrigating solutions used during vitrectomy, much higher than the 17 mmHg of the anterior vitreous or the 30 mmHg of the aqueous, may contribute to the oxidation of the proteins of the lens, thus accelerating the formation of cataracts. However, it remains to be demonstrated that this exposure to high levels of oxygen is maintained in the postop-

• Diabetes: there seems to be a lower rate of cataract progression in vitrectomized diabetics (especially in cases of ischemic retinopathy) compared to patients without diabetes, given that the oxygen level in their vitreous is lower

• Direct surgical damage: iatrogenic cataracts can be generated by direct trauma to the posterior lens capsule from the instruments used during pars plana vitrectomy, causing its rupture and producing a very rapid lens opacification. Trauma is more likely to be suffered in long difficult surgeries, such as retinal detachment with vitreoretinal proliferation. If a cataract is formed in the four months following retinal surgery, traumatic etiology should be suspected. [1, 20]

• Light toxicity: intense exposure to surgical microscope light or the fiber optic probe can be a factor that facilitates the oxidative damage of lens proteins. However, light sources currently incorporate Xenon light filter systems that eliminate the phototoxic fraction of the blue-ultraviolet wavelength, reducing

the phototoxicity caused in the lens or in the retina. [2]

*Development of a nuclear cataract in a diabetic patient after six months of vitrectomy.*

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**Figure 1.**

