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The Cryo-ROP study established exocryotherapy as a beneficial treatment
for threshold retinopathy of prematurity (ROP).1
More recently, the diode and argon indirect lasers have been used to treat
threshold ROP because they are technically easier to use and more easily tolerated
by the patient compared with cryotherapy.2-5
In addition, it has been demonstrated that a more confluent laser pattern
has a higher success rate than a less confluent laser pattern.6
Previously reported complications of cryotherapy include conjunctival and
subconjunctival hemorrhage, conjunctival laceration, elevated intraocular
pressure (IOP), and vision-threatening preretinal, retinal, or vitreous hemorrhage.7,8 Reported complications of laser
therapy include cataract development and hyphemas, and very rarely corneal,
iris, and lens burns and choroidal rupture with hemorrhages and subsequent
We report on cataracts, iris atrophy, and hypotony in 8 eyes of 5 patients
following confluent treatment for threshold ROP. None of the eyes demonstrated
a retinal detachment at the time the anterior segment changes were identified.
We feel that this represents an anterior segment ischemia.
Patients and Methods
Five patients were referred to William Beaumont Hospital in Royal Oak,
Mich, from January 1997 to July 1999 for evaluation of complications from
treatment of threshold ROP at various medical centers in the United States.
All 10 eyes of the 5 patients had been treated for threshold ROP. Seven of
the eyes that developed additional complications had been treated with diode
laser and 1 eye had been treated with cryotherapy. All 7 eyes underwent lensectomy
and vitrectomy. Two of the 7 eyes received silicone oil.
Report of Cases
A 570-g baby was born after 23 weeks' gestation. At 13 weeks of age
(36 weeks' postconceptual age [PCA]), the child was diagnosed as having threshold
ROP in both eyes and was treated with exocryotherapy in both eyes. Four days
after treatment the right eye was diagnosed as having a hyphema and corneal
haze. The ROP regressed without complication in the left eye.
The patient was referred to William Beaumont Hospital for evaluation.
Examination under anesthesia revealed regressed ROP in the left eye. Examination
of the right eye showed a cataract, iris atrophy, and hypotony. A lensectomy,
vitrectomy, and a fluid-air exchange were performed successfully. It was noted
during surgery that the retina was in good position except for a small radial
fold temporally. There was no evidence of active ROP. Follow-up examinations
showed the right eye to be phthisical.
A 592-g baby was born after a gestational period of 24 weeks 6 days.
At 8 weeks of age (33 weeks' PCA) the patient was diagnosed as having stage
3 threshold ROP. The patient received confluent laser treatment for both eyes
and developed bilateral hyphemas and cataracts. Partial lensectomies were
performed when the baby was 12 weeks old.
The patient was referred to William Beaumont Hospital for evaluation.
The right eye was soft with evidence of iris atrophy and had large lens pearls,
which reduced the view of the posterior pole. The left eye had a normal IOP
and anterior segment. Fundus examination demonstrated attached retina and
suggested regression of ROP. The patient underwent a vitrectomy, membrane
peeling, and removal of retained lens materials in both eyes. Subsequent follow-up
examinations showed both eyes to be phthisical.
A 705-g baby was born after 24 weeks 3 days' gestation. The patient
developed threshold ROP in both eyes at 8 weeks of age (33 weeks' PCA) and
was treated with confluent laser treatment to both eyes. The left eye responded
to the laser therapy and the retinopathy regressed. The right eye subsequently
developed large pupillary cysts and a cataract and became hypotonous.
The patient was referred to William Beaumont Hospital for evaluation
and had the cysts and lens surgically removed from the right eye. The retina
was attached and demonstrated evidence of regressed ROP; however, the eye
went on to develop phthisis.
A 790-g baby was born at 25 weeks' gestation. The patient went on to
develop threshold ROP in both eyes and was treated with laser photocoagulation
in both eyes at 38 weeks' PCA. Following laser treatment, the baby developed
severe posttreatment anterior segment inflammation in both eyes and bilateral
cataracts. One month after laser treatment, the patient underwent bilateral
lensectomies and vitrectomies. Two months after surgery the child was referred
to William Beaumont Hospital and the right eye was found, despite regressed
ROP, to have developed early phthisis. The left eye went on to develop a retinal
detachment secondary to advancing ROP and was treated with a second vitrectomy
and membrane peeling. This eye also went on to develop phthisis.
A 632-g baby was born at 24 weeks' gestation. The patient developed
threshold ROP in both eyes and at 14 weeks of age (38 weeks' PCA) was treated
with confluent laser treatment to both eyes. After treatment, both eyes developed
cataracts, iris atrophy, and hypotony (Figure
Anterior segment photograph of the right eye demonstrating a cataract
in a patient with iris atrophy and hypotony following confluent laser treatment
for retinopathy of prematurity.
The patient was referred for evaluation and underwent lensectomy, vitrectomy,
sector inferior iridotomy, and placement of silicone oil in both eyes. A follow-up
examination with the patient under anesthesia 1 week later revealed the IOP
to be 10 to 12 mm Hg. Fundus examination of both eyes demonstrated complete
laser treatment, retinal attachment, and regressed ROP. Postoperative examination,
6 months after placement of silicone oil, revealed a well-formed anterior
chamber, and ocular pressure, and globe contour were both normal.
Eight eyes were evaluated for complications following treatment for
threshold ROP and found to have signs of anterior segment ischemia including
cataracts, iris atrophy, hypotony, and corneal haze. Four of the 5 patients
were male and 5 of the eyes were right eyes. The birth weights ranged from
570 to 790 g, with a mean of 657 g. The PCA at the time of initial treatment
for threshold ROP ranged from 33 to 38 weeks with a mean of 35 weeks.
Six of the 8 eyes underwent lensectomy and vitrectomy with a fluid-air
exchange and yet still went on to develop phthisis. Two of the 8 eyes underwent
lensectomy and vitrectomy and received silicone oil instead of a fluid-air
exchange. These eyes had a beneficial anatomic result from this therapy.
Treatment for ROP, whether with cryotherapy or laser, has clearly proven
to be beneficial but is not without complication. This article sites vision
and ocular threatening complications from confluent laser or cryotherapy of
threshold ROP. Clinical examination of all eyes during examination with the
patient under anesthesia or at the time of lensectomy or vitrectomy revealed
confluent anterior retinal treatment, regression of threshold ROP, and the
absence of a retinal detachment in all the eyes. In addition, it should be
noted that the ciliary body was not accidentally treated in any of the cases
A possible mechanism for developing anterior segment ischemia following
treatment of ROP can be made by comparing laser treatment in proliferative
diabetic retinopathy with laser treatment in ROP. The major difference in
treating these diseases is the location and confluence of the laser burns.
Laser burn placement for the treatment of proliferative diabetic retinopathy
tends to spare the far peripheral portions of the retina. Treatment of ROP
includes the entire anterior avascular retina from the edge of the pars plicata
back to the anterior edge of the ridge of proliferative retinopathy covering
the entire circumference of the far peripheral retina. The long posterior
ciliary arteries travel along the horizontal meridians in the suprachoroidal
space and anastomose with the anterior ciliary arteries to form the anterior
vascular arcade and supply the anterior segment of the eye with blood. In
addition, during treatment of ROP there is significant scleral depression,
which could impair the circulation in the long posterior ciliary arteries.
Furthermore, treatment in the horizontal meridians tends to be more confluent
than in other areas because these sectors of retina are more accessible with
relation to the medial and lateral canthi. Impairment of blood flow and simultaneous
confluent tissue ablation could increase the risk of inducing anterior segment
ischemia that includes cataract, iris atrophy, and hypotony.
A potential treatment to preserve the physical structure of the eye
after this reported complication is with the use of silicone oil. The 2 eyes
in which silicone oil was placed maintained normal anatomic structure compared
with the eyes that only had a fluid-air exchange and went on to become hypotonous.
The adult and pediatric literature has reported on the safety of silicone
oil used for extended periods.12,13
It should be noted that follow-up for the eyes with silicone oil was for 6
months; therefore, it is possible that the anatomic success is only temporary.
There are reported side effects of using silicone oil, but at this time we
feel this treatment provides the best possible outcome for a difficult complication
of ROP treatment.
It has been the impression of many clinicians that confluent is a more
effective treatment than nonconfluent laser. We have identified a complication
of confluent treatment, but it may be avoided. Perhaps one should treat with
more space between laser burns or cryospots for the clock hours position of
the retina in the horizontal meridians to decrease the risk of ablating the
long ciliary arteries. This report should not discourage physicians from being
aggressive with the treatment of ROP but instead should prompt investigation
to further advance our methods of treatment and our understanding of its complications.
The authors have no conflicting commercial interests.
Presented at the Association for Research in Vision and Ophthalmology
annual meeting, Fort Lauderdale, Fla, May 2000.
Reprints not available from the authors.
Kaiser RS, Trese MT. Iris Atrophy, Cataracts, and Hypotony Following Peripheral Ablation for Threshold Retinopathy of Prematurity. Arch Ophthalmol. 2001;119(4):615–617. doi:
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