To compare refractive surgery outcomes in patients with different periods without contact lenses prior laser surgery, subjects who underwent myopic keratorefractive laser surgery between January 2005 and December 2014 were divided into three groups based on the duration of time passed free of soft contact lens wearing prior to final preoperative evaluation and surgery (<24 hours, one to three days or >three days). Spectacle wearers served as a control group. Postoperative safety index, efficacy index and percent of eyes within 0.5D of the four groups were compared. A general linear model was used to compare main outcomes while adjusting for age, gender, preoperative measurements and procedure type (LASIK vs PRK).

Overall, 19,747 eyes were included. Soft contact lenses were worn by 42.3% (<24 hours: 4.8%, one to three days: 18.5% and >three days: 19%) and spectacles by 57.7% prior to surgery. In the PRK group, after adjusting for differences in baseline variables, the <24-hour group had a significantly lower efficacy index than all the other groups. There were no significant differences between groups in terms of percent of eyes within ±0.5D of intended correction or safety index. In the LASIK group, after adjusting for differences in baseline variables, no significant differences were found between groups in all primary outcomes.

Researchers wrote that soft contact lenses should be removed at least 24 hours prior to final preoperative evaluation and refractive surgery, especially for patients undergoing PRK.

The management of intraocular pressure (IOP) is important for glaucoma treatment. IOP is recognized for showing seasonal fluctuation. Glaucoma patients can be at high risk of dry eye disease (DED). As such, investigators evaluated seasonal variation of IOP with and without DED in glaucoma patients. This study enrolled 4,708 patients, with a mean age of 55.2 years, who visited a clinic in Japan from March 2015 to February 2017. Investigators compared the seasonal variation in IOP (mean ± SD) across spring (March to May), summer (June to August), fall (September to November) and winter (December to February).

IOP was highest in winter and lowest in summer, at 14.2/13.7 for non-glaucoma without DED group (n=2,853, p=0.001), 14.5/13.6 for non-glaucoma with DED group (n=1,500, p=0.000), 14/13 for glaucoma without DED group (n=240, p=0.051) and 15.4/12.4 for glaucoma with DED group (n=115, p=0.015).

Seasonal variation was largest across the seasons in the glaucoma with DED group. IOP was also inversely correlated with corneal staining score. Investigators concluded that the seasonal variation was significant in most study groups and IOP may tend to be low in summer.

Contact lens comfort is influenced by a smooth transition of changes to the ocular surface epithelium, including cellular density. Conjunctival goblet cells are known to suppress activation of dendritic cells and therefore prevent inflammatory response. Hence, monitoring goblet cell numbers during lens adaptation could potentially facilitate comfortable lens wear. To explore the interlink between conjunctival goblet and corneal dendritic cell density after six months of lens wear and to predict dendritic cell migration to the central cornea based on goblet cell loss in the conjunctiva as a response to contact lens wear, 69 subjects who had never previously worn contact lenses were observed for six months; 46 were fitted with contact lenses and 21 served as a control group. Corneal confocal microscopy was used to quantify goblet and dendritic cell density before and after six months of daily lens wear. Symptomatic and asymptomatic groups were identified in the lens-wearing group using a combination of signs and symptoms present. Pearson's correlation was used to determine associations between the total change of cell densities after six months of lens wear.

At baseline, there was no association between conjunctival goblet and corneal dendritic cell density. After six months, there was an inverse association between the absolute change of conjunctival goblet and corneal dendritic cell density in all participants (n=69). Dendritic cell density in the central cornea was increased by 1.5 cells/mm² for every decrease of 1 goblet cell/mm² in the conjunctiva.

Researchers wrote, after six months of wear, contact lens-induced goblet cell loss can partially predict resident corneal dendritic cell migration to the central cornea (observed as an increase in dendritic cell density). They added that the association between total cell density change after six months was established in wearers regardless of lens symptomatology, suggesting that cell density changes as a physiological adaptation to regulate the effect of contact lens wear on the ocular surface.