healthmedicinet

This study was designed as a retrospective, consecutive, and comparative study. All
study protocols were approved by the Ethics Committee of Jikei University School of
Medicine and complied with the Declaration of Helsinki. Informed consent was obtained
from all subjects. Our study examined 35 eyes in 35 patients who had undergone combined
cataract surgery and 23-gauge transconjunctival vitrectomy for ERM (18 eyes) and RRD
(17 eyes) at Jikei University Hospital between January 2009 and July 2010 and for
whom the corneal thickness changes could be monitored for at least 3 months after
the initial surgery.

The mean ages of the patients were 52.9 ± 12.1 years in the RRD group and 72.0 ± 6.8 years
in the ERM group (Student’s t-test, p  0.001). Eyes were graded for nuclear sclerosis of the cataract according
to the Emery-Little classification guidelines. In the RRD group, 1 eye was classified
as grade 1, 8 eyes as grade 2, and 2 eyes as grade 3, with no eyes classified as grade
4. In the ERM group, 1 eye was classified as grade 1, 11 eyes as grade 2, and 6 eyes
as grade 3, with no eyes classified as grade 4. The mean axial length in the RRD group
was 25.0 ± 1.71 mm while it was 24.1 ± 1.81 mm in the ERM group (Student’s t-test, p = 0.18). The mean of the corneal thickness at the center in the RRD group
was 568.2 ± 27.0 µm while it was 554.4 ± 31.9 µm in the ERM group (Student’s t-test, p = 0.24). The mean surgical times in RRD and the ERM groups were 104.7 ± 26.2 min
and 54.3 ± 10.9 min, respectively (Student’s t-test, p 0.001).

Cataract and vitreous surgery procedure

All cataract and vitreous surgeries were performed by an experienced surgeon (W.A.)
at Jikei University Hospital. In both groups, the cataract surgery was performed via
a 2.4-mm superior corneoscleral incision at the 11 o’clock position, with an intraocular
lens implanted from same size corneoscleral incision.

We wrote about the common procedures about vitreous surgery in both groups below.
A DORC One-Step 23-Gauge Vitrectomy System
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was used to insert three ports in the transconjunctiva obliquely to the sclera to
perform vitreous surgery. Subsequently, a floating lens and irrigating hand-held lens
system were utilized to observe the fundus. If posterior vitreous detachment was not
present following the core vitrectomy, it was created during the vitreous surgery.
To ensure better visibility of the vitreous, we used triamcinolone acetonide during
the vitrectomy.

The subsequent surgical procedures that were used in the two groups were as follows.
In the RRD group, all procedures included peripheral vitrectomy with scleral depression
around the entire circumference, fluid gas (20 % SF6) exchange, and the performance
of internal drainage and laser photocoagulation around the tears during the surgery.
After each of the procedures, patients laid in a face-down position for 1–5 days.
In the ERM group, we performed core vitrectomy, peripheral vitrectomy with scleral
depression around the three ports and ERM peeling during the surgeries. In the ERM
group, 9 eyes (50 %) underwent internal limiting membrane (ILM) peeling. ILM removal
was performed by flushing 0.125 % ICG solution on the surface of the retina, which
made the ILM more visible.

Corneal thickness was measured using a Pentacam
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anterior segment analyzer (Oculus, Wetzlar, Germany) before and at 1 day, 1 week,
1 and 3 months after surgery. Measurements were performed at the center and at the
points 3 mm superior, inferior, nasal, and temporal to the center.

The degree of anterior segment inflammation was graded before surgery and at 1 day,
1 week, 1 and 3 months after the surgery. The degree of anterior segment inflammation
was graded qualitatively by slit-lamp examination using a method adapted from Barraquer
et al. 5]. Slit-lamp biomicroscopy was used to evaluate the anterior cell count and conducted
in a standardized fashion. Parameters used included dim room illumination, use of
the highest voltage lamp, a 0.5 × 2-mm aperture placed in the center area of the pupil,
use of a 30° illumination angle, magnification × 16x, and an observation time of 15 s.
A clinical inflammation score of the anterior chamber cell count was assessed in each
patient as follows: grade 0 = no cells, grade 0.5 = 1–5 cells, grade 1 = 6–15 cells,
grade 2 = 16–25 cells, grade 3 = 26–50 cells, Grade 5 = 50 cells 6]–8].

Measurement of the corneal endothelial cell count using a specular microscope was
performed before surgery and at 3 months after surgery.

We excluded all cases in which there were cataract surgery complications, corneal
epithelium removal during the vitrectomy, postoperative corneal epithelium damage,
high intraocular pressure 22 mmHg, or in which there had been intraocular surgery
performed within 1 year prior to the vitreous surgery.

For 4 weeks after the surgery, all patients were prescribed eye drops containing 0.5 %
levofloxacin hydrate, 0.1 % dexamethasone sodium phosphate and 0.1 % bromfenac sodium
hydrate. This was followed by the use of eye drops containing 0.5 % levofloxacin hydrate,
0.1 % fluorometholone and 0.1 % bromfenac sodium hydrate for an additional 3 months
after the surgery.

Statistical analysis

All statistical analyses were performed using statistical software programmed by Hisae
Yanai (Statcel-3, OMS Publication, Saitama, Japan).

Paired t-test was used to compare the postoperative corneal thickness with the preoperative
measurements in ERM and RRD groups.

The independent samples t-test was used in comparisons of ERM and RRD groups.

Wilcoxon signed-rank test was used to compare the postoperative degree of the anterior
segment inflammation with the preoperative measurements. Mann–Whitney U test was used
in comparisons of ERM and RRD groups.

Two-tailed P values of less than 0.05 were considered to indicate statistical significance.

Two-tailed P values of less than 0.005 (Bonferroni adjustments) were considered to
indicate statistical significance for multiple comparison.