A Pilot Study to Propose a "Harm Scale", a New Method to Predict Risk of Harm to the Corneal Endothelium Caused by Longitudinal Phacoemulsification, and the Subsequent Effect of Endothelial Damage on Post Operative Visual Acuity
January
A Pilot Study to Propose a "Harm Scale", a New Method to Predict Risk of Harm to the Corneal Endothelium Caused by Longitudinal Phacoemulsification, and the Subsequent Effect of Endothelial Damage on Post Operative Visual Acuity
Francesco Saverio Sorrentino 0
Claudio Bonifazzi 0
Francesco Parmeggiani 0
Paolo Perri 0
James Fielding Hejtmancik, National Eye
Institute, UNITED STATES
0 1 Department of Surgical Sciences, Unit of Ophthalmology, Ospedale Maggiore , Bologna , Italy , 2 Department of Biomedical and Surgical Sciences, Section of Human Physiology, University of Ferrara , Ferrara , Italy , 3 Department of Biomedical and Surgical Sciences, Division of Ophthalmology, University of Ferrara , Ferrara , Italy
-
There was a relationship between ECL percentage (ECL%) and the 5-score harm scale,
well-described by a linear model (one-way ANOVA, R2 = 73.3%). Analyzing the distribution
of ECL% Mean with Tukey post-hoc pairwise comparison test (P < 0.001), the value of
ECL = 20% has been regarded as cut-off to discriminate patients who obtained an excellent
postoperative best-corrected visual acuity (BCVA > 85 letters) from those who just had a
good visual outcome (BCVA 85 letters). There was a significant correlation among the
5To study the effect of longitudinal phacoemulsification energy on corneal endothelium and
to evaluate the relationship between changes of endothelial cells and postoperative visual
acuity.
This prospective clinical observational cohort study included 50 patients with cataract who
underwent longitudinal phacoemulsification. Sequential quantitative and qualitative
morphometric endothelial cell analyses of the cornea were performed 4 weeks preoperatively
and 6 weeks postoperatively using noncontact specular microscopy.
Data Availability Statement: All relevant data are
within the paper and its Supporting Information files.
Funding: The authors have no support or funding to
report.
Competing Interests: The authors have declared
that no competing interests exist.
Purpose
Methods
Results
score harm scale, phaco energy intraoperatively delivered, and average cell area
postoperatively.
Conclusions
The 5-score harm scale, a new method that enables to pigeonhole cataracts taking into
account nucleus hardness and phaco times, allows to predict the harm on corneal
endothelium after longitudinal phacoemulsification. Assessment of ECL% permits to discriminate
between patients with excellent BCVA and with just good BCVA, postoperatively.
Introduction
In last two decades, cataract surgery has been markedly improved by means of novel
techniques, new surgical equipment and viscoelastic agents [
1
]. Well-established
phacoemulsification techniques and well-experienced surgeons have done their utmost intraoperatively to
preserve the anatomical structure of the anterior chamber [
2,3
]. The care of corneal
endothelium has always been one of the main concerns of surgeons during phacoemulsification [
4–6
].
In fact, mechanical factors such as the jackhammer effect of longitudinal phaco cutting or the
implosion of microcavitation air bubbles cause heating and increased high pressure in the
anterior chamber [
7,8
]. Likewise, the ultrasonic power fluctuation, bouncing of fragments, the fluid
turbulence and increased production of free radical oxygen species cause great stress on
endothelium [
9,10
].
The corneal endothelium, which is derived from the neural crest, is a single layer of cells
that line the posterior corneal surface. Usually, the endothelial cells are hexagonal in shape and
uniform in size [
11
]. Throughout life the central endothelial cell density gradually decreases at
an average rate of about 0.6%/year [
12
], going approximately from 3400 cells/mm2 at age of 15
to 2300 cells/mm2 at age of 85 years [
13
]. Under normal circumstances, corneal endothelial
cells do not proliferate because they are stuck in the G1 phase of the cell cycle [
14,15
]. In case
of damage to the endothelium, for instance in corneal dystrophies or after intraocular surgery,
loss of endothelial cells results in the surviving cells changing in size and shape, becoming large
irregular shaped cells to cover the area previously occupied by the lost cells [16]. Acting as a
barrier and having a “pump-leak” function, the healthy endothelium is able to maintain the
corneal transparency and a well-balanced stromal hydration [
17
]. Non-contact specular and
confocal microscopy are extremely useful devices to clinically investigate and to easily give a
morphological evaluation of the corneal endothelium [
18
].
The purpose of this study was to investigate the effect of energy delivered into the anterior
chamber and analyze changes and injury on corneal endothelial cells after longitudinal
phacoemulsification. We have used statistical criteria to evaluate the association between phaco times
and endothelial damage. To better clarify this correlation, we constructed a Likert-type scale to
(...truncated)