 |
|
LASIK-Associated Visual Field Loss in a Glaucoma Suspect
Arch Ophthalmol. 2001;119:774-775.
We report a case of visual field loss first noted after laser in situ
keratomileusis (LASIK). One similar case has been described.1
Since LASIK involves brief iatrogenic elevation of intraocular pressure (IOP),
we are concerned about the possible rare instances of this occurrence in future
patients.
Report of a Case
A 47-year-old high myope received a diagnosis of ocular hypertension
in 1979 with an IOP of 30 OU. Her mother and sister had glaucoma. Treatment
with 0.5% timolol maleate maintained her IOP in the high teens except for
an occasional IOP in the low 20s. Findings on Humphrey 24-2 visual field testing
were normal on June 4, 1997 (Figure 1).
|
|
|
|
Figure 1. Normal Humphrey 24-2 visual field
test of patient on June 4, 1997. POS indicates positive; NEG, negative; DS,
diopter sphere; and DC, diopter cylinder.
|
|
|
On June 16,1999, an experienced surgeon (R.S.R.) performed LASIK for
correction of 10.5 diopters (D) of myopia in the right eye and 9.5 D of myopia
in the left. Pachymetry measured a 473-µm thickness OU preoperatively
and a 360-µm thickness OD and 390-µm thickness OS postoperatively.
During the week postsurgery the patient noted a new paracentral scotoma in
her left eye. On June 25, 1999, visual field testing showed the presence of
a previously undocumented scotoma superotemporal to fixation in the left eye
(Figure 2). A notch was noted on
the corresponding aspect of the optic nerve. Latanoprost was added as treatment
for both eyes and the patient was sent for glaucoma consultation.
|
|
|
|
Figure 2. Visual field testing shown of
a previously undocumented scotoma superotemporal to fixation in the left eye
of the patient, June 25, 1999. POS indicates positive; NEG, negative; DS,
diopter sphere; and DC, diopter cylinder.
|
|
|
On August 23, 1999, uncorrected vision was 20/20 OD and 20/25 OS. Her
IOP was 12 mm Hg 3 hours after treatment with 0.5% timolol and latanoprost
OD and 17 mm Hg 3 hours after latanoprost therapy OS. Pupils were normal with
no afferent defect. Five iris transillumination defects were present in the
left eye; none were present in the right. No Kruckenberg spindle was present
in either eye. Posner gonioscopy revealed an angle open to the ciliary body
band for 360° in both eyes with marked pigmentation of the posterior trabecular
meshwork in the left eye more than in the right eye. The cup-disc ratio was
0.6 OD and 0.7 OS with peripapillary atrophy and temporal sloping in both
eyes. The diagnosis of open-angle glaucoma with a component of pigment dispersion
was made. The patient was relieved to consider the possibility that the visual
field change may have occurred in association with the LASIK procedure, rather
than due to concurrent progression of the underlying disease.
The IOP has measured in the low teens OU when treated with 0.5% timolol
and latanoprost, though her readings may be falsely low owing to her thin
corneas. Visual field testing on December 1, 1999, showed no progression of
the scotoma (Figure 3).
|
|
|
|
Figure 3. Visual field testing of patient
on December 1, 1999, showed no progression of the scotoma. POS indicatives
positive; NEG, negative; DS, diopter sphere; and DC, diopter cylinder.
|
|
|
Comment
An experienced LASIK surgeon can limit the duration of the iatrogenic
increase in IOP during LASIK to approximately 10 seconds. During this time
a mechanical suction ring achieves a pressure of approximately 80 mm Hg. Although
the brevity of the pressure elevation suggests that most optic nerves could
tolerate the procedure, the severity of the pressure elevation suggests that,
at least occasionally, mechanical compression or ischemia may damage an optic
nerve. The stress of pressure elevation in LASIK is of shorter duration but
greater magnitude compared with gravity inversion2
or high-resistance wind instrument playing,3
activities that have been associated with elevated IOP and abnormal visual
fields.
Inspection of the optic nerve prior to LASIK may allow identification
of some of the patients who are at risk. Features of the optic nerve that
may be of concern are the same variables that identify early glaucomatous
optic nerve damage: vertical cup–disc diameter ratio corrected for optic
disc size, total neuroretinal rim area, rim–disc area ratio, and cup–disc
area ratio corrected for disc size.4 Patients
with glaucoma, a family history of glaucoma, as well as glaucoma suspects
should be cautioned of this risk prior to the performance of LASIK. For many
of these patients, photorefractive keratectomy, intrastromal corneal ring
segments, or continued use of contact lenses or eyeglasses may offer satisfactory
vision without subjecting the optic nerve to the small but real risk of pressure-associated
visual field loss.
Howard S. Weiss, MD, MPH;
Roy S. Rubinfeld, MD;
John F. Anderschat, MD
Washington, DC
REFERENCES
1. Bushley DM, Parmley VC, Paglen P. Visual field defect associated with laser in situ keratomileusis. Am J Ophthalmol. 2000;129:668-671.
PUBMED
2. Sanborn GE, Friberg TR, Allen R. Optic nerve dysfunction during gravity inversion. Arch Ophthalmol. 1987;105:774-776.
ABSTRACT
3. Schuman JS, Massicotte EC, Connolly S, et al. Increased intraocular pressure and visual field defects in high resistance
wind instrument players. Ophthalmology. 2000;107:127-133.
FULL TEXT
|
ISI
| PUBMED
4. Jonas JB, Bergua A, Schmitz-Valckenberg P, et al. Ranking of optic disc variables for detection of glaucomatous optic
nerve damage. Invest Ophthalmol Vis Sci. 2000;41:1764-1773.
FREE FULL TEXT
THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES
Influence of post-LASIK corneal healing on scanning laser polarimetric measurement of the retinal nerve fibre layer thickness
Hollo et al.
Br. J. Ophthalmol. 2002;86:627-631.
ABSTRACT
| FULL TEXT
|
