In this prospective, non-randomised study, we compared the effect of the intraoperative Mydrane protocol (MP) and the preoperative standard mydriatic-anaesthetic protocol (SP) on the ocular surface evaluated after cataract surgery.
All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee (the Institutional Review Board of the University of Florence), and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all individual participants included in the study.
Sixty eyes of 60 patients were evaluated and analysed. The first 30 patients were included in the MP group and the following 30 patients in the SP group. Patients with a bilateral cataract participated with only one eye in the study.
Exclusion criteria were the use of contact lenses; history of previous corneal surgery; mild and severe DED confirmed by Schirmer’s test I (STI) < 10 mm; tear break-up time (TBUT) < 7 s; Ocular Surface Disease Index (OSDI) score > 22; severe blepharitis; corneal dystrophies; corneal keratopathies; eyelid abnormalities (floppy eyelid syndrome, lagophthalmos); continuous use of topical or systemic medication (including the use of tamsulosin) that could affect the corneal surface and the pupillary dynamics; previous complicated cataract surgery that required the application of a suture; and cataract hardness grade ≥ 3 as per the Lens Opacities Classification System III .
At inclusion, data on patient age, current treatments and medical and ocular history were collected. Clinical assessments were performed at baseline (Day − 1; pre-assessment) and at days 1, 5 and 15 after cataract surgery (referred to hereafter as Days 1, 5 and 15, respectively). Patients underwent a complete ophthalmological examination on both eyes, including best-corrected visual acuity using the Snellen chart, slit lamp examination and intraocular pressure measurement. The following ocular surface parameters were evaluated: STI and TBUT. All patients completed an OSDI questionnaire for assessment of the ocular symptoms score at baseline and Days 5 and 15. Flare and cells in the aqueous humour were measured at baseline and at Days 5 and 15 using an FC-2000 laser flare-cell meter (Kowa Co., Ltd., Nagoya, Japan) in a dark room following the manufacturer’s guidelines; the mean of the remaining five readings were automatically calculated by the instrument and expressed in photons per milliseconds .
The Optical Scattering Index (OSI) and its standard deviation (OSI-SD) were assessed using the Optical Quality Analyzing System (OQAS; Visiometrics S.L., Barcelona, Spain), a non-invasive, double-pass system aberrometer, at Days 1, 5 and 15. This system evaluates aberrations and scattering caused by the optical system as well as the tear film quality during the interblink period . The tear film analysis program of OQAS records dynamic changes in OSI values and calculates the mean OSI value for 20 s. The OSI provides an objective evaluation of the intraocular scattered light, with a higher OSI value corresponding to a higher intraocular scattering level. For eyes with a normal degree of scattering, the OSI value is < 0.5.
Keratocyte activation, Langerhans’ cell density (LCD), nerve fibre density (NFD) and endothelial cell density (ECD) were assessed on serial optical sections (approx. 400 × 400 μm) by in vivo confocal microscopy (IVCM) using a retina tomograph (Heidelberg retina tomograph version 3; Heidelberg Engineering Inc., Heidelberg, Germany) equipped with the Rostock Cornea Module, at baseline and at Days 5 and 15. Central corneal thickness (CCT) was measured at baseline and at all postoperative visits using spectraldomain optical coherence tomography (RTVue-100; Optovue Inc., Fremont CA, USA) with the addition of an anterior segment module (CAM-L mode).
Eyes of the patients in the SP group received one drop of tropicamide 0.5% and phenylephrine 10% prior to surgery, with the procedure repeated three times at 10-min intervals starting 30 min before surgery, while eyes of the patients in the MP group were injected with 200 μL of tropicamide/phenylephrine/lidocaine in the
anterior chamber immediately after the first corneal incision. The eyes of both groups were given two drops of oxybuprocaine hydrochloride 0.4% prior to the first incision, and the eye lid and conjunctival sac of all eyes were disinfected with 10 and 5% povido-iodine solution (Oftasteril), respectively.
All surgical interventions were performed by the same expert surgeon (RM). After topical anaesthesia had been applied, a temporal corneal tunnel incision and a capsulorrhexis of about 5.5 mm were performed. Phacoemulsification using the stop and chop technique was performed using the Centurion® Vision System (Alcon Laboratories Inc., Geneva, Switzerland).
Irrigation of the eye was carried out using 10 cl of balanced salt solution, and the time and power of ultrasonic phacoemulsification were recorded; blood pressure before and after drug injection as well as the colour of the iris were noted. At the end of surgery, intracameral cefuroxime (Aprokam®; Farmila-Thea, Settimo Milanese, Italy) was injected into the anterior chamber of the eyes in both groups.
The postoperative medication regimen included topical treatments with chloramphenicol 0.25%/betamethasone 0.1% (Betabioptal; Laboratoires Théa) 4 times a day for 2 weeks, and 0.9 mg/ml bromfenac solution (Yellox; Bausch & Lomb-IOM S.p.A., Macherio, Italy) twice daily for 1 month. No other treatments were allowed.
Data analysis was performed using the Statistical Package for Social Sciences (version 20.0 for Windows; IBM Corp., Armonk, NY, USA). An estimate of the sample size was obtained a priori based on the Student’s t test for two independent samples at an α level equal to 5% for comparison between groups, and for two paired samples at an α level equal to 5% for comparison within groups.
Data distribution was analysed by the Shapiro–Wilk normality test for each data group. The differences between preoperative and postoperative assessments were analysed using the t test for paired samples. The differences between eyes/patients in the MP and SP groups were analysed for each parameter by the t test nonparametric test for two independent samples. Differences yielding a P value < 0.05 were considered to be statistically significant.