Refractive surgery in patients with retinitis pigmentosa.

Abstract

To evaluate the refractive outcomes and safety of laser refractive surgery in a group of myopic patients with retinitis pigmentosa (RP).
This was a multicenter, retrospective, noncomparative, interventional case series. A total of 32 eyes of 16 patients with RP with at least 18 months of follow-up were treated with laser refractive surgery (photorefractive keratectomy [PRK], laser subepithelial keratectomy [LASEK]). Refractive outcomes, complete eye examination, corneal topography, and retinal sensitivities were evaluated during follow-up. Mean follow-up was 28.3 months (minimum 18, maximum 50). Mean patient age was 29.6 years (range 24-54). Mean best-corrected visual acuity (BCVA) was 0.75 preoperatively.
Eighteen months after surgery, mean uncorrected visual acuity (UCVA) was 0.8+/-1 line (p=0.02); mean BCVA was 0.85+/-1 line (p<0.0005) with mean spherical equivalent of -0.16 D. Corneal complications were not detected during follow-up; corneal topography did not show corneal ectasia in any patient after surgery. During follow-up visits, no development or progress of macular edema was noted in any eye. Retinal sensitivities increased after surgery; there were no significant changes in electroretinogram amplitude.
Mean UCVA and BCVA 18 months after surgery were higher than preoperative BCVA. All patients were safely treated without any significant complications. Our results support the safety of performing PRK and LASEK in patients with tapetoretinal degeneration.

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© 2010 Wichtig Editore - 1120-6721
Eur J Ophthalmol(2010;
:
2) 271-27520
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ORIGINAL ARTICLE
INTRODUCTION
Retinitis pigmentosa (RP) is a group of clinically and genet-
ically heterogeneous retinal degenerations characterized
by chronic progressive loss of rod and cone function (1).
The disease can be inherited as an autosomal dominant
(about 30%–40% of cases), autosomal recessive (50%–
60%), or X-linked (5%–15%) trait. Non-mendelian inheri-
tance patterns, such as digenic inheritance and maternal
(mitochondrial) inheritance, have been reported but prob-
ably account for only a small proportion of cases (2, 3).
In RP , rod system damage is more prominent, so that effects
on central vision are variable and some patients can maintain
good visual acuity throughout their lives, despite extinguished
electroretinogram and visual field (VF) reduction (4).
Previous research showed higher incidence of myopic and
cylindrical refractive errors in the RP population compared
to the normal population (5).
Laser refractive surgery allows us to correct low to mild refrac-
tive errors, reducing spectacle dependence and often improv-
ing quality of vision by reduction of corneal aberrations.
Different studies reported association between RP and
keratoconus; moreover, the incidence of corneal ectasia
after laser in situ keratomileusis (LASIK) has been esti-
mated to be 0.2% to 0.66%, whereas it has rarely been
reported after photorefractive keratectomy (PRK) or laser
Refractive surgery in patients with retinitis pigmentosa
Enzo Maria Vingolo1,2, Pier Luigi Grenga1,2, Alessandro Meduri3, Stefano Lupo4, Roberto Grenga4
1Department of Ophthalmology, A. Fiorini Hospital, Terracina, University of Roma “La Sapienza”, Roma
2Ophthalmology, S.M. Goretti Hospital, Latina
3Department of Surgical Specialties, Ophthalmology Clinic, University of Messina, Messina
4Department of Ophthalmology, Policlinico Umberto I, Roma, University of Roma “La Sapienza”, Roma - Italy
PurPose. To evaluate the refractive outcomes and safety of laser refractive surgery in a group of myo-
pic patients with retinitis pigmentosa (RP).
Methods. This was a multicenter, retrospective, noncomparative, interventional case series. A total of
32 eyes of 16 patients with RP with at least 18 months of follow-up were treated with laser refrac-
tive surgery (photorefractive keratectomy [PRK], laser subepithelial keratectomy [LASEK]). Refractive
outcomes, complete eye examination, corneal topography, and retinal sensitivities were evaluated
during follow-up. Mean follow-up was 28.3 months (minimum 18, maximum 50). Mean patient age
was 29.6 years (range 24–54). Mean best-corrected visual acuity (BCVA) was 0.75 preoperatively.
results. Eighteen months after surgery, mean uncorrected visual acuity (UCVA) was 0.8±1 line (p=0.02);
mean BCVA was 0.85±1 line (p<0.0005) with mean spherical equivalent of –0.16 D. Corneal complications
were not detected during follow-up; corneal topography did not show corneal ectasia in any patient after
surgery. During follow-up visits, no development or progress of macular edema was noted in any eye. Reti-
nal sensitivities increased after surgery; there were no significant changes in electroretinogram amplitude.
ConClusions. Mean UCVA and BCVA 18 months after surgery were higher than preoperative BCVA.
All patients were safely treated without any significant complications. Our results support the safety
of performing PRK and LASEK in patients with tapetoretinal degeneration. (Eur J Ophthalmol 2010;
20: 271-5)
Key Words. Refractive surgery, Retinitis pigmentosa
Accepted: August 11, 2009

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Refractive surgery in patients with retinitis pigmentosa
eters were used: a fixation target consisting of a 2-degree-
diameter red cross, a white monochromatic background at
4 asb, stimulus size Goldmann III, with 200 ms projection
time, and a customized grid of 45 stimuli covering 10° cen-
tered onto the fovea. Decibel range was 0–20 (400 and 4
asb, respectively). A strategy 4-2-1 double staircase was
used; the initial level of retinal sensitivity was set at 8 dB.
Stimuli with MP-1 were always projected exactly onto pre-
defined retinal positions by means of an eye tracker that
compensates the eye movements. All subjects underwent
microperimetry with dilated pupils.
Patients included in this study fulfilled general candidacy
criteria for refractive surgery. Exclusion criteria were chron-
ic uveitis, previous herpetic keratitis, keratoconus, corne-
al dystrophy, diabetic retinopathy, and further typical RP
complications such as cystoid macular edema (CME) and
cataract. None of the patients had previously undergone
cataract surgery. Cardiovascular pathologies, pregnancy,
immunosuppressive treatments, neurologic disorders,
conditions associated with alterations of the cicatrization
process, some autoimmune and collagenous diseases,
and diabetes mellitus were excluded as well.
Informed consent was obtained before the patients un-
derwent laser surgery. All the procedures adhered to the
tenets of the Declaration of Helsinki.
All the operations were bilaterally and simultaneously per-
formed from 1999 to 2006, by 2 different surface ablation
procedures and 2 different surgeons in 2 different sites.
Nine patients (18 eyes) underwent LASEK, according to the
technique of Vinciguerra et al (13). Seven patients (14 eyes)
underwent PRK as follows: after mechanical removal of the
superficial layer of corneal epithelium, photoablation was
carried out to a central area with a diameter of 6 mm and
proportional depth of the entity of the refractive problem;
at the end of the operation, a therapeutic contact lens was
positioned in the eye to reduce pain (Sky Soft Monthly).
Postoperatively, topical clobetasone 1% and tobramycin
0.03% were used in all cases with dosage of 4 times a day
in a tapered dose for 10 weeks.
Laser platforms were Bausch & Lomb C-217 and
Mel-70 G-Scan Zeiss excimer laser for LASEK and
PRK procedures, respectively. Algorithms were con-
ventional for all patients.
Paired t tests were used to compare the mean visual acuity
and retinal sensitivity scores between the preoperative and
18-month postoperative outcomes. Statistical calculations
have been done from individual logMAR acuity data, not
subepithelial keratectomy (LASEK) (6-11).
In the current literature, there are no significant studies re-
porting surgical outcomes and long-term safety in patients
with RP who undergo refractive surgery.
The aim of our study was to evaluate the refractive out-
comes and safety of laser refractive surgery, by surface ab-
lation procedures, in a group of myopic patients with RP.
MATERIALS AND METHODS
The charts of 16 patients (32 eyes) with RP, managed be-
tween 1999 and 2006, and submitted to laser refractive
surgery, were included in this multicenter retrospective
noncomparative interventional case series. Institutional
Review Board (IRB) permission was granted for the retro-
spective chart review.
Data collection included uncorrected visual acuity (UCVA),
best-corrected visual acuity (BCVA), manifest and cycloplegic
refractions, corneal topography (Tomey TMS-2), evaluation of
tear secretion using a Schirmer test, fundus examination, VF,
full-field electroretinogram (ERG), and microperimetry.
Patients were scheduled for clinical evaluation preopera-
tively, the same day, 1 week, and 1, 3, and every 6 months
postoperatively. Patients with at least 18 months of follow-
up were included in the study.
VF, ERG, and microperimetry tests were recorded preoper-
atively and 1 month and 18 months after surgery. Only pa-
tients submitted to surgery since 2003 (n=10) were evalu-
ated by microperimetry. Corneal topography was repeated
18 months after surgery in all patients.
UCVA and BCVA were measured with a projected Snel-
len chart adjusted for a 5-meter viewing distance with a
luminance of 65 cd/m2; contrast of the chart was calcu-
lated as 89%. The data in this article are shown as decimal
equivalents.
Standard automated perimetry tests were performed, for
all patients, using a Humphrey Field Analyzer model 745
(Zeiss Humphrey Systems, Dublin, CA) with the SITA stan-
dard 30-2 test; if fixation losses and false positive or false
negative rates were >20%, the test was repeated.
ERG analyses were performed by Metrovision ERG ma-
chine according to ISCEV standards evaluating maximum
amplitude (a–b wave) as previously described (12).
Microperimetry was performed since 2002 in 10 patients
(20 eyes), with the automatic fundus-related perimeter (MP-
1 Nidek Technologies, Japan). In our study, these param-

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Vingolo et al
lines preoperatively, preoperative SE was –4.3 D; 1 year af-
ter surgery, mean UCVA was 0.84±1 line, mean BCVA was
0.89±1 line (p<0.005) with mean SE of –0.02 D.
In 20 eyes submitted to preoperative and postoperative
microperimetric examination, mean preoperative reti-
nal sensitivity was 10.26±1.22 dB, 1 month after surgery
was 10.59±1.71 dB, and 12 months after surgery was
10.88±1.30 dB (p<0.0001).
Preoperative ERG in 23 eyes was nonrecordable and in 9
was subnormal (b-wave mean amplitude: 7.68±2.26 µV);
18 months after surgery, in 23 eyes was nonrecordable and
in 9 was subnormal (b-wave mean amplitude 7.56±2.87
µV).
VF examination showed 22.56±5.51 dB; 1 month after sur-
gery it was 23.77±6.28 dB and 18 months after surgery it
was 24.11±5.93 dB (p<0.0001).
Our patients had no intraoperative or postoperative com-
plications; corneal complications were not detected during
follow-up. Corneal topography 18 months after surgery did
not show corneal ectasia in any patient. During follow-up
visits development or progress of CME was not detected in
any eye. CME assessment was performed by ophthalmo-
scopic examination and after 2001 by OCT (Stratus OCT,
Carl Zeiss). Our RP patients, during normal follow-up, are
submitted to OCT every 12 months.
DISCUSSION
Our study indicated a favorable refractive outcome after
laser refractive surgery, by surface ablation procedures, in
patients with RP. Our follow-up did not show complications
related to refractive surgery.
Mean UCVA and BCVA 18 months after surgery were high-
er than preoperative BCVA. Mean SE after surgery was
–0.16 D; consequently, no patients needed enhancement
surgery. A total of 6.25% of eyes lost 1 or more Snellen
lines of visual acuity 18 months after surgery (Fig. 1).
Our experience showed a slight difference between the 2
procedures. Twelve months after surgery, mean UCVA were
0.81 and 0.84 in the PRK and LASEK group, respectively.
VF examination and microperimetric tests showed that
mean retinal sensitivities increased 18 months after sur-
gery; ERG amplitude had no significant changes.
The reduction of spectacle-induced aberrations could be
the reason why VA and retinal sensitivities increased af-
ter surgery; the ERG b-wave value changes were not sig-
decimal, and then converted back to decimal, according to
the procedure outlined by Holladay (14). Both eyes of each
patient were studied, and were analyzed separately.
RESULTS
Mean follow-up was 28.37 months (minimum 18–maxi-
mum 50). Mean patient age was 29.7 years (range 24–54).
Pattern of inheritance was autosomal dominant RP for 4
patients, X-linked RP for 5 patients, and autosomal reces-
sive RP for 7 patients (Tab. I).
Mean BCVA and standard deviation were 0.75±1.5 lines
(decimal units) preoperatively, preoperative spherical
equivalent (SE) was –5.39 D (range –2 to –13 D), mean pre-
operative cylinder was –1.84 D (range –0.5 to –3.00 D), and
average K was 43.64 D.
Mean BCVA 3 months after surgery was 0.81±1 line, post-
operative SE was –0.07, mean postoperative cylinder was
–0.63 D, and average K was 40 D; mean UCVA 3 months
after surgery was 0.79±1 line.
One year after surgery, mean UCVA was 0.83±1 line
(p=0.02), mean BCVA was 0.89±1 line (p<0.0005) with
mean SE of –0.11 D, mean cylinder was –0.71 D, and aver-
age K was 39.81 D.
Eighteen months after surgery, mean UCVA was 0.80±1
line (p=0.02), mean BCVA was 0.85±1 line (p<0.0005) with
mean SE of –0.16 D, mean cylinder was –0.73 D, and aver-
age K was 39.76 D.
No patients needed enhancement surgery for myopic shift
or for recurrence of refractive error.
We analyzed differences between the 2 procedures. Mean
BCVA was 0.78±1.5 line preoperatively in the PRK group
(14 eyes), preoperative SE was –4.5 D; 1 year after surgery,
mean UCVA was 0.81±1 line, mean BCVA was 0.89±0.5
line (p=0.05) with mean SE of –0.21 D.
In the LASEK group (18 eyes), mean BCVA was 0.74±1.5
TABLE I - CLINICAL DETAILS OF PATIENTS
Parameters

No. (male/female)
Mean age, y (range)
Mean follow-up, y (range)
Pattern of nheritance, ADRP/ARRP/XLRP
Results
16 (7/9)
29.6 (24–54)
28.3 (18–50)
4/7/5
ADRP = autosomal dominant retinitis pigmentosa; ARRP = autosomal recessive
retinitis pigmentosa; XLRP = X-linked retinitis pigmentosa.

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Refractive surgery in patients with retinitis pigmentosa
frequent cause of central visual loss in patients with RP;
we evaluated retinal thickness and the presence of macu-
lar cysts by means of OCT after 2001. OCT has been de-
scribed as a useful procedure to determine the presence
of CME and it is likely more sensitive for identifying cystic
lesions than FA (16-18). Overall, the likelihood of induced
CME seems low given that surface ablation was done with-
out intraocular intrusion and without the suction forces that
LASIK would have required.
Patients must be extensively informed about the limita-
tions of visual recovery due to retinal dystrophies in order
for refractive surgery to be ethically acceptable in patients
with RP.
In conclusion, this retrospective study presents the
largest number of patients with RP who had refractive
surgery to date. Our results support the safety of per-
forming surface ablation procedures in patients with RP
without central vision involvement.
Presented in part at the annual meeting of the American Academy of Ophthal-
mology, November 2007 (Poster 413).
The authors report no proprietary interest or financial support.
Address for correspondence:
PierLuigi Grenga, MD
Viale Carlo Felice 101
00185 Roma, Italy
plgrenga@hotmail.it
nificant. All patients were satisfied after refractive surgery
and particularly spectacle independence was important for
them, even if affected by rod-cone dystrophy.
Our study is the first to examine safety of refractive sur-
gery in RP patients. Walraedt et al (15) reported 3 cases
of patients affected by retinal inherited dystrophies and
submitted to LASIK, in those patients retinal dystrophies
diagnosis has been made after refractive surgery be-
cause patients complained poor vision, corneal topogra-
phy years after surgery did not show corneal ectasia or
dystrophies, retinal sensitivities were not evaluated in that
case report. This study demonstrates the importance of
preoperative evaluation in order to exclude patients with
cone-rod dystrophies and retinal inherited disease involv-
ing central vision.
The main objective of our research was to evaluate safety
of laser refractive surgery, by surface ablation procedures,
in a group of patients with RP. After 18 months, no patients
had corneal complications. Patients with follow-up longer
than 36 months (n=5) did not show any anterior segment
complications. We performed surface procedures instead
of LASIK because surface ablation is considered to induce
less structural destabilization than LASIK for the same giv-
en correction due to the absence of the flap in weakened
corneas (8). Different studies reported association between
keratoconus and RP (6, 7).
Retinal sensitivities evaluated by ERG, VF, and, in a group of
patients, by microperimeter were not reduced after surgery.
During follow-up, any patients did not show CME, it is a
Fig. 1 - Change in best-corrected visual acuity
bar graph (32 eyes, 18 months postoperative).

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Vingolo et al
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