Pharmacological Management in Pseudomyopia

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Case Study

Aastha Subedi, B. Optom

B.P Koirala Lions Center for Ophthalmic Studies, Institute of Medicine, Nepal

Author correspondence: aasthasubedi7@gmail.com

Ethical issues: Participants may feel a slight discomfort during instillation of eye drops. However, this discomfort is minor and will ameliorate within minutes. The use of dilating drops may cause pupil dilation and slight blurring of vision for up to 24 hours.

Statement of consent: After explaining all the procedures and objectives of the study, an assent was taken from the participant and an informed verbal consent was taken from her legal guardian.

Financial support: None

Key words: Accommodation, Accommodative excess, Cycloplegia, Convergence

Abstract

This is a case report of a 12-year-old girl with pseudomyopia, which was managed pharmacologically. The symptoms and detailed binocular vision evaluation along with cycloplegic refraction suggested pseudomyopia or accommodative excess. Along with visual hygiene, Tropicamide eye drops were prescribed for use at bedtime in both eyes for 2 weeks.

Introduction

Accommodative excess is a condition in which patient has difficulty with all tasks requiring relaxation of accommodation. Here, accommodation doesn’t relax even when viewing at distance. Exerting excess amount of accommodation for a certain period of time causes spasm of accommodation. Accommodative excess is the initial stage of accommodative spasm. Patients with accommodative excess typically exhibit increases in myopia or decreases in hyperopia. In accommodative excess, accommodative response exceeds accommodative stimulus.

This report presents a case of psuedomyopia related to accommodation excess that was managed with Tropicamide eye drops.

Case presentation

A 12-year-old girl presented to us with chief complaint of gradual painless diminution of vision for 1 month (for both distance and near). Apart from blurring of vision, the associated symptoms were headache, eyestrain and difficulty focusing from far to near, particularly during near activities. The patient first noticed these symptoms towards the end of her vacation. According to the patient, the blurring of vision, headache and eyestrain seemed to worsen towards the end of the day and were particularly bothersome when she was under any stress. The patient had no history of any medical treatment nor double vision, nausea, dizziness, any associated mental stress and any other systemic illness. There was no history of use of eyeglasses or any other interventions with no past ocular diseases and surgery. Indeed, this was her first visit for an eye checkup. There was no history of systemic or ocular diseases in her family members.

Visual acuity:

The unaided Visual Acuity in Right eye and Left eye were 6/9P and 6/9 respectively.

Ocular health:

Both anterior and posterior segments were normal.

Refraction:

The static dry retinoscopy in both eyes were -2.75 D However, the subjective acceptance was only -0.50 D in both eyes.

The refractive evaluation did not show consistent findings according to the symptoms, so a thorough binocular vision evaluation was performed.

Binocular Vision Assessment:

The cover test for distance and near indicated Orthophoria and 4Δ Esophoria, respectively. Convergence test, which was done with the dot in RAF ruler, showed 7 cm objectively and 10 cm subjectively. The amplitude of accommodation with the N5 target was 6.5 D monocularly and 7D binocularly. The Negative Fusional Vergence (NFV) for near and distance were 8Δ and 6Δ, respectively. The Positive Fusional Vergence (PFV) was 12Δ for near and 6Δ distance. Flipper test as done with +/- 2.00 D indicated 4 cycles per minute monocularly and 5 cycles per minute binocularly, with difficulty for a plus lens in both cases. The Negative Relative Accommodation (NRA) and Positive Relative Accommodation (PRA) was +1.50 D and -4.00 D, respectively. Dynamic retinoscopy as performed with Monocular Estimation Method revealed -2.25 D lead of accommodation.

Since the objective retinoscopy finding and subjective acceptance were considerably different, we decided on cycloplegic refraction as per the protocol of the institute. Cycloplegic refraction was carried out after detailed binocular vision assessment and refraction, with one drop of Cyclopentolate, Tropicamide, and Cyclopentolate administered successively in a 10-minutes time interval. Cycloplegic retinoscopy revealed +0.25 D in both eyes.

Provisional diagnosis

Based on the clinical findings obtained, the following provisional diagnoses were made.

Accommodative excess:  This diagnosis was based on the accommodative lead in dynamic retinoscopy, difficulty with plus lens (difficulty in relaxation of accommodation) on accommodative facility test and a high Positive Relative Accommodation (PRA) and low Negative Relative Accommodation (NRA) findings.

Pseudomyopia: This diagnosis was based on a relatively more myopic refractive error in static retinoscopy as compared to subjective refraction and a low myopic refractive error in cycloplegic retinoscopy.

Clinical Management

The patient was advised to practice visual hygiene (i.e., regular breaks during near work, reduction in near work at the end of the day, and 20-20-20 rule). Along with it, the patient has prescribed Tropicamide eye drops (1%), one drop at a time, at bedtime in both eyes for 2 weeks. The static retinoscopy was -0.50 D in both eyes which was -2.25D earlier, at the time time of presentation. The accommodative amplitude was 8.33D in both eyes which were 6.25D earlier. Negative Fusional Vergence (NFV) at near and distance improved from 8Δ BI and 6Δ BI to 14ΔBI and 8Δ BI, respectively.  After 2 weeks, the patient had very good compliance with no any side effects associated with Tropicamide eye drops. At the follow-up visit, the patient was advised regular installation of Tropicamide eye drops at bedtime for a further two weeks along with visual hygiene.

Discussion

Since the patient was very symptomatic we applied pharmacological treatment for instant relief rather than optical treatment. Since the accommodative relaxation therapies are time-consuming, we moved on to pharmacological intervention. A retrospective case series study was done at a tertiary eye care hospital in Chennai, India. Four patients presented with complains of sudden onset of blurring of vision and asthenopic symptoms with history of aggravation of symptoms with prolonged near work and stressful conditions. Refraction though showed myopic refractive error initially, showed hyperopic shift after cycloplegia. Diagnosis of accommodative spasm was made. Bifocal glasses were prescribed and atropinization (1%) with avoidance of aggravating factors was started. Patients were tapered gradually to prevent recurrence over three months and observed for six months in which none had a recurrence. Post cycloplegia, the condition resolved and asthenopic symptoms were improved. (1)

Spasm of near reflex is a very severe form of accommodative excess. A sustained period of accommodative excess could lead to accommodative spasm. The later may be associated with limitation of abduction along with severe myopia and miosis. Pseudomyopia is a condition where the static, dry retinoscopic error is significantly more myopic than actual error revealed by cycloplegic refraction. It occurs when a spasm of the ciliary muscle prevents the eye from focusing in the distance, sometimes intermittently, which is different from myopia caused by the eye’s shape or basic ocular anatomy. (2)

Literature suggests that the short-term application of 0.25% tropicamide eye drop could relieve the accommodative spasm of adolescent pseudomyopia with good efficacy and feasibility. Tropicamide eyedrop was instilled at 68 adolescents (136 eyes) with pseudomyopia and visual acuity were analyzed based on the chi-square test. They found that there was a significant difference in visual acuity before and after treatment (P=<0.05). (3) Conventionally, the treatment of pseudomyopia is dependent on the underlying aetiology. Functionally, pseudomyopia is managed through modification of working condition, an updated refraction, typically involving reduction of myopic prescription or through appropriate relaxation exercises. A retrospective study was done to assess accommodative excess cases, it’s diagnosis without the use of cycloplegic drugs along with the utility of vision therapy protocol. This protocol was developed in Ikusgune Optometric Center (Donostia, Spain). The sessions with the optometrists were 45 minutes and at home were 4 to 5 times per week and 20 minutes each being supervised by the parents in patients under 14 years with exercises taught by the optometrist. Here, 24 patients diagnosed with accommodative excess completed 8-12 sessions of vision therapy protocol. The pairwise comparisons of sphere values obtained with the different refractive methods without cycloplegic drugs found statistically significant differences (P<0.01), as shown in the sphere values obtained from subjective refraction, visual acuity tests, near point of convergence and stereopsis between the diagnostic visit and the post-therapy visit. The effects of the refraction method findings, autorefractor sphere values, retinoscopy sphere values and subjective refraction with and without cycloplegic sphere values were assessed and compared. (1)

Contradictory finding

Insufficiency of amplitude of accommodation is one & only contradictory finding in this case. Since this finding suggests difficulty to accommodate whereas other findings are in alignment with difficulty to relax accommodation (i.e., accommodative excess). After 1 month of second visit, we prescribed +0.75 D in both eyes as per the patient’s acceptance that contributes to improve insufficiency of accommodation.

References

  1. Kavthekar A, Shruti N, Nivean M, Nishanth M. Accommodative spasm: Case series. TNOA J Ophthalmic Sci Res 2017;55:301-3
  2. Scheiman M, Wick B. Clinical management of binocular vision: heterophoric, accommodative, and eye movement disorders. Lippincott Williams & Wilkins; 2008.
  3. Gaohong WU. Clinical efficacy of tropicamide eyedrop in treatment adolescent pseudomyopia. Chinese Journal of Primary Medicine and Pharmacy. 2012 Jan 1(8):1135-6.
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