A delicate, thin membrane seen over the crystalline lens can be material adherent to the top of the lens capsule or splitting of part of the anterior capsule. The patient has no history of eye disease, has no signs or findings suggestive of anterior uveitis, and did not sustain ocular trauma. The membrane is flat, thin, and colorless; therefore, a fibrinous membrane is unlikely.
Splitting of the anterior capsule is the landmark of exfoliation syndrome; however, this typically occurs after prolonged exposure to extreme heat and infrared irradiation. Although spontaneous splitting of the anterior capsule is not common, it has been reported in numerous cases. A superficial lamella is peeled off the anterior capsule to create a diaphanous, free-floating, membrane-like flap. The typical triangular shape of the flap, simulating the initiation of surgical capsulorhexis, is clearly seen in Figure 2. Capsule splitting is often presented as a double-ring sign when, during capsulorhexis, both the anterior and posterior lamellae are dissected separately in parallel directions.
There is some confusion in the terminology of capsular exfoliation. Exfoliation syndrome (glassblower's cataract) is sometimes termed true exfoliation as opposed to the PEX syndrome; however, spontaneous splitting of the anterior capsule is also often called true exfoliation. Capsular delamination is probably a better term for this phenomenon.
The most important thing regarding capsular splitting is making the correct diagnosis. Failure to recognize that only part of the capsule was removed by the capsulorhexis might be associated with severe trauma to the lens when phacoemulsification is attempted before the anterior capsule is opened. Once the surgeon realizes that peeling the thin anterior lamella did not create a full-thickness capsule opening, a second capsulorhexis would be created. Usually, the use of capsule dye is not required if there is a good red reflex. Phacoemulsification and IOL implantation would then be done in the regular fashion. In most cases, the surgical prognosis is excellent, the capsule remains stable and intact, the zonules are not affected, and there are no other long-term complications of capsular delamination.