Micro-incision 25g pars plana vitrectomy (PPV) does not affect the tear film osmolarity of patients who did not suffer from other eye or systemic diseases, according to a study published in BMC Ophthalmology.

The prospective study included 21 patients (17 females) who underwent 25g PPV surgery to treat macular hole or epimacular membrane. Ocular surface diseases, use of artificial tears prior to surgery, intraocular diseases, trauma, or prior surgery other than cataract surgery were considered exclusion criteria.

Researchers measured tear film osmolarity in both eyes of all patients before the procedure, 10 days after surgery, and 30 days after surgery. They used a paired test for statistical evaluation. The mean osmolarity of the operated eyes before surgery was 299.00 mOsmol/L. At day 10 postoperative it was 303.86 mOsmol/L. By day 30 it was 297.38 mOsmol/L


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“No statistically significant change in osmolarity was found in the operated eyes (P >.05). No statistically significant changes in time (P >.05) were found when both eyes were compared. There were no postoperative complications or failure to observe the study protocol,” they report. 

Researchers suggest this finding challenges previous opinions that inflammation or postoperative damage to the ocular surface leads to hyperosmolarity. 

In addition, investigators write that this study seems to be “among the first to investigate changes in osmolarity after micro-incision vitrectomy.” And because it found that micro-incision, uncomplicated 25g PPV didn’t impact osmolarity in those who didn’t have other eye or systemic diseases, the next question is whether PPV performed in complicated diagnoses, such as diabetic retinopathy, can affect osmolarity. 

The study’s limitations include its small sample size, though the authors report that they took care to take samples with maximum objectivity.

Reference

Němčanský J, Kopecký A, Mašek P. Changes in tear film osmolarity after 25g+ PPV. BMC Ophthalmol. (2020)20:452. doi: 1186/s12886-020-01722-4