|ENDOTHELIAL CELL IN ARK PRACTICE
UP TO 7 YEARS
SANGUBASHI EYE CLINIC GOTANDA
Institute of Refractive
Summary: In l983 I Iecived Anterior Radial
Keratotomy to both eyes at the moscow Research Institute of Eye Mierosurgery
from Professor S.N. Fyodorov. 1)
|I want to report on the excellent results achieved over the past 7 years using
ARK on patients in Japan. Also I would like to show the complete safty of this
procedure. Using a speculer microscope and putting the data through corneal
endothelial cell computer norphologic analyzer.
I will present the
histories of 17 eyes in 9 patients. One eye was uemotropic and didn't need
correction. These 9 patients were all members of my family or my friend's
families. All these patients gave informed consent.
method : ARK
was performed on l7 eyes of 9 patients. The ages of all the subjects at the time
of completion of this study are over 25 years old (average 32.5 years) and all
of them had more then -2.50 diopters myopia.
Three out of the nine wore
contact lenses regulary. (2RL,5RL and 9RL)
All cases except 3R had no
previous history of disease. Case 3R had keratitis, while wearing a hard contact
lense at the age of 22. All of the patients had naked vision less than 0.3 and
a corrected visual acuity of more than1.0. Before ARK a video and written matter
were used to explain the procedure to the patients. All patients are given
corneometry as well as the standard examinations. The standard procedure
developed by Prof. Fyodorov4) usd for ARK seven years ago and photographs were
obtained of corneal endothelial cells using a Konan specular microscope and a
morphometric cell analyzer, used to obtain cell counted the degree of
polimegethism and pleomrphism. Case 2R,5RL and 9R were reoperatet and one case
9L was reoperated twice with the purpose of increasing the effect.
magnification is calibrated with a micrometer scale. Thirty cells are outlined.
The cells are digitized by touching the cell apices with a graphic tablet pen.
These coordinates are entered on to a digitizer table and analyzed by computer
for cell density, standard deviation (SD), coefficient variation (CV), average
of cell area (AVE), maximum of cell area (MAX), minimum of cell area (MIN), and
a histogram is made. .
Cell density is calculated by dividing one milion
by the mean cell area.
CV is calculated by dividing the SD of cell area by
the mean cell area.
Polimegethism is assessed indipendently of cell size
using a dimentionlless index for CV. 'Normal endothelial cells are about 300
microns square in size and hexagonal. Inflamation or injury can reduce cell
count, hexagonality and uniformity of size. Eyes with exessive deviation in any
of the above are not considered as candidates for ARK.
Visual acuity in all eyes having had ARK had stabilized after four months.
(Fig.2,3 and4) Tables 3 and 4show change in corneal refraction and visual
acuity before and 7 years after. According to the size of the optical zone and
the number of cuts, the resulting corneal refractive power can be decreased from
1 to 8 diopters. Out of 17 cases, one case (6L) of superficial keratotitis
occured. It was treated with a two week course of gentamycin subconjunctive
injection and a wide-spectrum antibiotic. After 7 years there are no
complications and the cornea remains transparent. (Fig. 5)
microscopic analysis shows mean cell densities of 2,347 cells per square mm
between the incisions, standard deviation 122, coefficient variation 3l, average
of cell area 426, maxmum of cell area 658, minimum of cell area l73 microns
Slight increases in nonhexagonal cell (pleomorphism), and a
variation in cell size (polimorphism) are observed. Case 3R had a history of
Specular microscopic analysis shows mean cell densities of
1,869 cells per square mm between the incisions, standard deviation 151,
coefficient variation 28, average of cell 635, maxmum of cell area 818, minimum
of cell area 162 microns square.(Fig.8) As the specular microscope only became
available in 1986, preoperative data is not available for l7 cases, including
this case. We can keep record of yearly rates of cell loss.
For 121 eyes in
61 patients from l987 to l988 the immediate cell loss a result of operating is
Discussion : Since the first pioneering work done by
Professor Fyodorov and others in 1974, over 327,000 people have recived ARK.3)
There have been, however, only limited reports of long term effects and sporadic
reports on safty and effectiveness of ARK. Because of high satisfaction and lack
of complications and the subsequent non-return of patients to the clinic, ther.e
is limited statistical information available. There is in the case of Japan a
certain resistance in the old establishment to ARK, because of the unfortunate
experience with Professor Sato's posterior radial ke.atotomy (PRK) in 1936.
Therefore I make this report.
The result of ARK remains constant between 4
months and 7 years after operating. The changing refraction is limited to 8
diopters. The patient must be informed of this prior to operating. In six cases
mild myopia aged 35 to 40 years, none wore glasses or contact
lenses after seven years. (3RL,4RL,5L,6R,7L and 8RL) .
moderate or severe cases of myopia, low grade glasses are worn when driving, at
theatre or in some cases constantly, which doesn't affect the field of vision as
those wore previously. So nine cases discontinued use of contact lenses after
ARK. Those that required lenses, were first examined at eight to twelve months
with a specular microscope as a precautionar.y check.
glare and or starburst effect are noted.
Post-operative astigmatism not
requiring corrective lenses was noted in cases 3R, 4R and 5RL. In cases 3R and
4R are 0.75 diopters, 5R is 1.00 diopter and in 5L is 1.50 diopters.
like to make one final point about endothelial cell dynamics over the long term
after ARE. Bullous keratopathy is not a possible result postoperatie
endothelial cell loss of 5.9% , thereafter continuing at a
coinciding with Dr.Murphy's 0.35 to 0.71% per year.(Fig.7)
reoperated showed a similar cell loss. At this rate of endothelial cell loss,
a person would have to live to the age of 166 years before the critical level
of 500 cells per square mm would be reached.
So specular microscopic
examination is done before operation in order to facilitate obtaining informed
consent as well as obtaining data to follow up post-operative cell loss and also
the yearly rate of cell loss.
In the case of finding unusualy high levels
of polymegethisn or polimozphism, these people are rejected for ARK. We find as
did Dr.Scott, a higher incidence of such conditions among long term contact lens
This could be a result of previous histories of infection.
We mesured endothelial cell loss and plotted the information for 121 eyes in
61 patients on a graph similar to Dr.Myer's endothelial cell depletion
graph.(Fig.2) On his graph a 35 year old person will have 2700 endothelial
cells per square mm. If such a person loses 5.9% as an immediate result of ARK
and we calculate natural aging cell loss of 0.35 to 0.71% ( according to Dr.
Murphy ), then at the age of forty-two he should have 2,457 endothelial cells
per square mm. But in practice our forty-two year old patient has 2,816
endothelial cells per square mm in his right eyes and 3,355 cells in his left
eye.(Fig.9,10) In the other seven cases we recorded a similar high result.
(Fig.11) One case 3R was lower and should continue to be observed over the
Up till now 1,500 patients have received ARK at our clinic.
i) K.Okuyama : myopia is possible to operate
within 15 minutes.
Tokyo, Kobunsha p92-150, 1985
2) D.J.Mayer : Clinical
wide-field specular microscopy.
Bailliere Tindall, London p52-53, 1984
3) S.N.Fyodorov, A.I.Ivashina : Microsurgery of the eye- Main aspects.
Mir. Publihers. Moscow p68-70, 1987
4) S.N.Fyodorov, V.V.Durnev : Operation of dorsaged dissection of corneal
circular ligament in cases of myopia of mild degree.
Annals of Ophthalmology p1986-1989, l979 Dec.
5) T.Yamaguchi et al. : Bullous keratopathy after anterior-posterior radial
keratotomy for myopia and myopic astigmatism.
Am. J. Opthalmol. 93:600.
6) Scott M Mac Rae et al. : The effects of hard and soft contact lenses
on the corneal endothelium. Am. J. Ophthalmol. p50-57, July 1986
7) Scott M. Mac Rae et al. : The effect of radial keratotomy on the corneal
endothelium. Am. J. Ophthalmol. p538-542, October, l985