Reclaiming Vision: Scleral Lens Fitting After Acanthamoeba Infection

Introduction

Acanthamoeba is a free-living unicellular protozoon commonly found in fresh water and soil. The protozoa can be found in two forms: a metabolically active trophozoite and a resistant cyst. Acanthamoeba keratitis (AK) is an infection primarily associated with soft contact lens wearers who demonstrate improper contact lens hygiene practices, such as noncompliance with disinfection systems, cleaning lenses with tap water, or swimming while wearing lenses. Approximately 85% of cases of AK in developed countries are associated with contact lens wearers. The overall incidence of AK in the United States is 1.49-2.01 cases per million contact lens users per year. Individuals suffering from AK often experience a significant decrease in visual acuity and pain that is disproportionate to their clinical signs^1-2.

Clinical Presentation

A 54-year-old female presented for a corneal evaluation due to decreased vision and severe right eye pain. She had a history of being treated for suspected Herpes Simplex Virus (HSV) and neurotropic keratitis 2-3 months prior to being seen at Havener Eye Institute without symptomatic relief. She also had a history of primary soft contact lens wear due to poor adaptation to vision in spectacles. She discontinued contact lens wear due to symptoms.

Chief Complaint: pain, blurry vision, tearing, burning, photophobia OD

Ocular History: corneal ulcer and scar OD

Ocular Surgeries: none

Ocular medication:

Failed Therapies:

- Autologous Serum 6-8x per day OD

- Ofloxacin QID

- Prednisolone acetate 1% ophthalmic suspension BID

- Cyclosporine Ophthalmic Emulsion 0.05% BID OU

- Erythromycin ointment QPM OD

- Cenegermin-bkbj ophthalmic solution 0.002% 6x per day

- Valacyclovir 1g PO BID

- Amniotic membrane

Entering Testing and Slit Lamp Findings	OD	OS
Entering Uncorrected VA	HM (PH: NI)	20/150 (PH: 20/40)
Intraocular Pressure	10mmHg	9mmHg
External	Reactive ptosis	No Abnormalities
Lids/Lashes	No Abnormalities	No Abnormalities
Conjunctiva/Sclera	2-3+ injection	White and Quiet
Cornea	Diffuse Punctate Epithelial Erosions Central Circular Anterior Stromal Scar with Surrounding Haze Overlying Epithelial Defect	All layers clear
Anterior Chamber	Deep and Quiet	Deep and Quiet
Iris	Round and Reactive	Round and Reactive
Lens	Clear	Clear

Table 1. Entrance Testing and Slit Lamp Examination

Figure 1 and 2. Slit lamp external photography of the patient’s right eye showing diffuse punctate epithelial erosions, a central circular anterior stromal scar with surrounding haze, and an overlying epithelial defect.

Methods and Results

Due to no improvement despite therapy, as well as a history of soft contact lens abuse and noncompliance, a corneal culture of the right eye was obtained. PCR results were positive for Acanthamoeba spp.

Treatment and Management

Moxifloxacin TID OD

Chlorhexidine QID OD

PHMB Q1H OD

Cyclopentolate BID

Valacyclovir 1g PO BID

Contact Lens Fitting

OD: Upon resolution of active infection, the patient was referred by the corneal service for a scleral lens evaluation

OS: The patient was refit into a daily disposable soft contact lens

Post Infectious Testing and Slit Lamp Findings	OD	OS
Entering VA w/ spectacles	CF at 3’ (PH: 20/200-1)	20/25+2
Intraocular Pressure	10mmHg	9mmHg
External	Reactive ptosis	No Abnormalities
Lids/Lashes	No Abnormalities	No Abnormalities
Conjunctiva/Sclera	White and Quiet	White and Quiet
Cornea	Mild irregular epithelium overlying a central scar Faint neovascularization Stromal haze	All layers clear
Anterior Chamber	Deep and Quiet	Deep and Quiet
Iris	Round and Reactive	Round and Reactive
Lens	Clear	Clear

Table 2. Post Infectious Testing and Slit Lamp Examination

Figure 3. Slit lamp photography of, OD, central scar and stromal haze

Figure 4. OD (right) and OS (left): Scheimpflug tomography

Clinical Outcome

BCVA: 20/40+2

Mild irregular corneal epithelium overlying a central scar, faint neovascularization, and stromal haze

No staining upon removal

BCVA: 20/20

Well centered fit with adequate coverage and movement

No staining upon removal

Final Lens Parameters
Eye	Lens	Diameter (mm)	Base Curve (mm)	Power (D)	Material	Total Sag
OD	BostonSight SCLERALTM	18.0	8.0	+0.75DS	Contamac Optimum Infinite	2750
OS	Alcon Dailies Total 1TM	14.1	8.5	-2.75DS	Deleficon A	N/A

Table 3. Final Lens Parameters

Discussion

Patients suffering from AK present with eye pain, lacrimation, redness, blurred vision, and foreign body sensation. AK usually presents unilaterally, with only 7.5% of cases presenting bilaterally^1-2. Early clinical indicators of AK include an irregular epithelium and pseudodendrites, which can advance to radial keratoneuritis, as well as diffuse or focal anterior stromal ring infiltrates. In severe cases, AK may progress to conditions such as limbitis, scleritis, uveitis, and corneal melt, potentially resulting in perforation if untreated.

Diagnosis of AK can be challenging due to the variance in clinical signs and symptoms. HSV keratitis, fungal keratitis, and Pseudomonas keratitis are all important differential diagnosis to consider. However, early detection of AK is the most critical factor for achieving a favorable visual outcome due to the infection being limited to the superficial cornea. The average delay in diagnosis of AK is 50 days after the first presentation of symptoms. If the disease persists for more than 4 weeks without appropriate treatment, the final visual prognosis is less favorable with 25% of AK cases result in the need of a penetrating keratoplasty^3-4.

Figure 5. Slit lamp photography of, OD, final scleral lens with an optic section

Figure 6. Slit lamp photography of, OD, final scleral lens in primary gaze

Conclusion

A high clinical suspicion of AK should be present in primary contact lens wearers with a history of noncompliance. Corneal culture or confocal microscopy are imperative in identifying corneal pathology when conventional treatment is ineffective. The current treatment approach for AK involves debridement of the infected epithelium as well as PHMB and Chlorhexidine with medical treatment lasting 3-6 months^3-4. Scleral lenses are indicated after the active disease process has subsided to provide the best visual outcome over resulting corneal scars, sub epithelial haze, and irregular astigmatism. Educating and emphasizing proper contact lens hygiene is vitally important in insuring the corneal health of patients.

References

1. Büchele MLC, Nunes BF, Filippin-Monteiro FB, Caumo KS. Diagnosis and treatment of Acanthamoeba Keratitis: A scoping review demonstrating unfavorable outcomes. Cont Lens Anterior Eye. 2023;46(4):101844. doi:10.1016/j.clae.2023.101844

2. de Lacerda AG, Lira M. Acanthamoeba keratitis: a review of biology, pathophysiology and epidemiology. Ophthalmic Physiol Opt. 2021;41(1):116-135. doi:10.1111/opo.12752

3. Dos Santos DL, Virginio VG, Berté FK, et al. Clinical and molecular diagnosis of Acanthamoeba keratitis in contact lens wearers in southern Brazil reveals the presence of an endosymbiont. Parasitol Res. 2022;121(5):1447-1454. doi:10.1007/s00436-022-07474-y

4. Kaufman AR, Tu EY. Advances in the management of Acanthamoeba keratitis: A review of the literature and synthesized algorithmic approach. Ocul Surf. 2022;25:26-36. doi:10.1016/j.jtos.2022.04.003