Photophobia is a general term
used to describe light sensitivity or abnormal intolerance to light. Patients
with photophobia avoid light because of pain or discomfort. Although it
may be encountered in disorders of the iris and anterior segment of the
eye, photophobia may also be reported in patients with completely normal
appearing anterior segments. Some of these conditions include blepharospasm,
migraine, meningitis, sub-arachnoid hemorrhage, and head injury. Although
not completely understood, the mechanism of photophobia is thought to
involve the trigeminal pathway and possibly input from the occipital lobe
and thalamus. Irritation to any region supplied by the trigeminal nerve
can facilitate photophobia.
1 Benign essential blepharospasm is
a movement disorder characterized by involuntary spasmodic contraction
of the eyelids.
2 Patients often report that
the symptoms are initiated and exacerbated by sensitivity to both ambient
and bright light.
3 Results from a recent, University
of Utah survey indicate that photophobia occurs in over 90% of patients
with blepharospasm.
4 The spasms are physically and often socially debilitating, making normal
activities such as reading, driving, and working difficult to perform.
In severe cases the patient can be rendered functionally blind.
Photophobia has been studied in patients with migraine headaches because
ninety percent of migraine patients report light sensitivity during and
between attacks.
5 Another University of Utah
study demonstrated that blepharospasm patients are more light sensitive
than age-matched control subjects and that the degree of light sensitivity
in these patients was similar to that of migraine patients.
6 This study also showed that
lenses with either gray tint or FL-41 tint, a tint first described in
Birmingham England for use with children with migraine headaches, improved
light sensitivity in blepharospasm patients. Although there was no significant,
measurable difference in improvement of light tolerance between gray tint
and FL-41 tint, patients anecdotally reported FL-41 lenses to be more
effective.
Because FL-41 tint blocks visible light at the blue end of the spectrum,
a subsequent University of Utah study investigated the physical difference
in retinal photopigments in patients with blepharospasm. This study revealed
that blepharospasm patients had a statistically significant increase in
photopigment levels when compared to normal patients. 4
Objectives
The purpose of this study is to determine if Fl-41 tinted spectacles are
more effective in reducing symptoms of blepharospasm and photophobia in
patients with benign essential blepharospasm compared with a standard,
neutral gray tint.
Patient Selection Criteria
There are no previous studies of FL-41 tint in blepharospasm. From anecdotal
evidence, we estimate that 20% of patients prefer gray tint, 50% of patients
prefer FL-41 and 20% have no preference. Using  = 0.05 and
 = 0.8, the sample size required is 22 patients.
Because the number of subjects required is estimated based solely on blepharospasm.
Patients will have been diagnosed by either one of the principal investigators
or by one of three other ophthalmologists familiar with this condition,
Drs Judith E A Warner, Richard A Anderson or Bhupendra C K Patel. Patients
must have a history of involuntary contraction of the
orbicularis oculi muscles for one year or more. The spasms should be evident
on clinical examination. Patients with other eye conditions that could
cause photophobia will be excluded, including iritis. Patients already
using FL-41 tinted spectacles will also be excluded.
Blepharospasm is exclusively a disease of adults, male and female. No
children will be enrolled.
Design
This study will have an unmasked double-cross over design. Patients will
be randomized by a coin toss to start in either the gray tinted spectacle
group or the FL-41 spectacle group.
Procedures
Informed consent will be obtained from each subject. Patients will fill
out a baseline questionnaire to evaluate the severity of their symptoms,
and the effect these symptoms have on their quality of life. This questionnaire
was developed for and used in a previous University of Utah study. 4
A coin flip will be used to randomize patients into two treatment groups.
Group 1 will use gray tinted spectacles. Group 2 will use FL-41 tinted
spectacles. Subjects in each group will be asked to wear the spectacles
indoors and outdoors at all times, for a period of two weeks. At the end
of two weeks, each subject will be asked to fill out another questionnaire
to evaluate the effect the spectacles had on their symptoms and on their
quality of life. At that time, the groups will crossover: Group 1 will
now wear FL-41 spectacles and Group 2 will wear gray tinted spectacles.
At the end of the second, two-week period, subjects will fill out a third
and final questionnaire.
Statistical Methods
At the end of the project, the responses to the questionnaires will be
tabulated using a Microsoft Excel spreadsheet. A mean and a standard deviation
will be determined for each numerical response on the questionnaire. Student’s
t-test will be then be used to determine if there is a statistically significant
difference between the two groups for each questionnaire response.
1. Main A, Dowson A, Gross M. Photophobia and phonophobia in migraineurs
between attacks. Headache 1997;37:492-495.
2. McCann JD, Gauthier M, Morschbacher R et al. A novel mechanism for
benign essential blepharospasm. Ophthalmic Plastic and Reconstructive
Surgery 1999;15:348-389.
3. Anderson RL. Blepharospasm: Past, Present, and Future. Ophthalmic Plastic
and Reconstructive Surgery 1998;14:305-317.
4. Judd R, Adams W, Digre K et al. Light Sensitivity in Blepharospasm
Patients. Annual Meeting of the North American Neuro-Ophthalmology Society.
Snowbird, UT; 2003:110.
5. Vanagaite J, Pareja JA,
Storen O et al. Light-induced discomfort and pain in migraine. Cephalgia
1997;17:733-741.
6. Adams W, Digre K, Warner J et al. Light Sensitivity in Patients with
Blepharospasm. Annual Meeting of the North American Neuro-Ophthalmology
Society. Copper Mountain, CO; 2002:122.
Does this research involve human subjects or animals? No
If yes, what is the protocol number? 11873
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