Changes in the anterior segment of the eye following uncomplicated pars plana vitrectomy. A review

Changes in tear film osmolarity after 25G+ PPV

Background

The aim of our study was to assess changes of tear film osmolarity after micro-incision 25G+ pars plana vitrectomy (PPV) in a prospective study.

Methods

The group consisted of 21 patients (17 women, 4 men) with an average age of 70,52 years [48; 85]. All patients underwent 25G + PPV surgery due to a disorder of the vitreomacular interface (macular hole or epimacular membrane). Only patients who did not use artificial tears before the surgery and who had not been diagnosed with dry eye syndrome at ours or another institution were included in the study. Except cataract surgery, all ocular surface diseases, intraocular diseases, trauma or surgery were exclusion criterias.

Tear film osmolarity was measured in both eyes in every patient before surgery, 10 days after surgery and 30 days after surgery. A paired test was used for statistical evaluation.

Results

No statistically significant change in osmolarity was found in the operated eyes (p > 0.05). No statistically significant changes in time (p > 0.05) were found when both eyes were compared. There were no postoperative complications or failure to observe the study protocol.

Conclusion

Micro-incision 25G + PPV does not affect the osmolarity of the tear film.

Stepwise Decreasing of Vitreous Pressure by Anterior Vitrectomy: A Novel Method for Preventing Positive Vitreous Pressure During Penetrating Keratoplasty

BACKGROUND

This study evaluates the clinical effects of the stepwise anterior vitrectomy on the prevention of positive vitreous pressure (PVP) during penetrating keratoplasty (PKP).

METHODS

PKP in conjunction with stepwise anterior vitrectomy was performed on 15 eyes of 15 patients under retrobulbar anesthesia. A preset vitrectomy trocar-cannula was inserted into the vitreous cavity before PKP. During the opening of the anterior chamber, intermittent vitrectomy and corneal incision expansion were performed alternately to keep the lens or artificial intraocular lens (IOL) and iris flat until the entirety of the pathological cornea had been dissected. The main outcome measures include visual acuity, crystalline lens rise (CLR), corneal curvature and diopter, and corneal endothelial cell loss.

RESULTS

All surgical procedures were performed successfully without any PVP-related intraoperative complications. The mean time of the stepwise vitrectomies was 3.1 ± 0.7 s, the duration of each vitrectomy was 8.1 ± 5.3 s, and the duration of the total surgery was 60.5 ± 5.3 min. The anterior segment reaction was mild and the shape of the pupil remained normal 1 day after surgery. The mean preoperative and mean 3-month postoperative CLR values were 0.48 ± 0.09 mm and - 0.16 ± 0.04 mm, respectively (p < 0.0001). The mean preoperative endothelial cell density in donor buttons was 2570 ± 171 cells/mm², and the mean 6- and 12-month postoperative endothelial cell density in donor buttons was 2207 ± 127 cells/mm² and 2000 ± 198 cells/mm², respectively.

CONCLUSIONS

The novel and stabilized PKP procedure, performed in conjunction with the stepwise anterior vitrectomy, effectively avoided the PVP during open-sky surgery.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR1900021227.