Photodynamic Therapy (PDT), introduced to ophthalmology in 2000, is a therapeutic procedure which utilizes the photosensitive intravenous drug, verteporfin (Visudyne, Bausch & Lomb) in combination with a low power, long duration infrared laser. In the eye, it is used to treat vascular issues in the retina and choroid. It was first indicated for neovascular age related macular degeneration (AMD), with large randomized clinical trials showed an improvement in visual acuity versus placebo. Photodynamic therapy’s role in ophthalmology was spurred by the success of the treatment of AMD with PDT (TAP) and Verteporfin in PDT (VIP) studies. The studies proved PDT’s efficacy in treating AMD patients with classical subfoveal choroidal neovascularization. As new therapies have evolved, it is now typically used as a second-line treatment for neovascular AMD. PDT is now most often used to effectively treat cases of Central Serous Retinopathy (CSR) and have been shown to be efficacious by several published studies.
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Retinal diseases such as Retinitis pigmentosa, Choroidal atrophy, Retinoschisis, High myopia with uveal coloboma etc.
Retinal detachment surgeries
They are usually symptomatic and associated with a reduction in visual acuity.
Likely originate from the pigment epithelium of the iris or ciliary body and later become detached into the vitreous
They are brown in color
Congenital cysts are usually non-pigmented and originate from the hyaloidal vascular system
They are translucent, mobile and yellow-gray in color.
Congenital cysts are choristomas (normal tissues growing in abnormal location) of the primary hyaloidal system
Derived from the pigment epithelium of the iris or ciliary body
Contains immature melanosomes
Light & Electron Microscopy:
Orellana et al studied aspirated pigmented cyst by light microscopy and electron microscopy.
They found that the pigmented layer of cuboidal cells contains large mature melanosomes and few immature melanosomes suggesting origin from the pigment epithelium.
Pathophysiology of Acquired Cysts
Trauma can cause damage to the pigment epithelium of ciliary body and create pigment cysts
Other theories: Vitreous reaction to underlying retinal degeneration can causes cysts, Ciliary adenoma breaking into the vitreous, cystic growths that occur at site of coloboma that enter the vitreous
These are often noted on clinical examination at the slit lamp or with funduscopy.
History of ocular trauma
History of infections or inflammations of the eye
History of ocular surgery
History of ocular disease such as: uveitis, uveal coloboma, retinoschisis, retinitis pigmentosa, retinal detachment and ocular malignancies
Age of patients usually between 10-20 years
Mostly unilateral, but bilateral cases have also been reported especially in retinitis pigmentosa
When a cyst floats into and obstructs the visual axis, patients can complain of transient blurring of vision, floaters, shifting visual field defects and occasionally photophobia.
Signs and Morphological appearance of the cysts
Numbers and Positioning: Single unilateral, Single Bilateral, Multiple unilateral
Dimensions: 0.15-12 mm
Shapes: Spherical, Oval, Lobulated
Surface: Smooth or Crenated
Color: Yellow-gray (non-pigmented) or Brown (Pigmented)
Location: Confined to the region of Cloquet’s canal
The cysts can move with a patient’s eye movements while examining with an indirect ophthalmoscope.A colour fundus photo showing a well-defined round parasitic cyst of cysticercosis in the vitreous cavity Photo Courtesy- Rajan Eye Care Hospital, Chennai
A detailed clinical examination is required to rule out other infectious and malignant conditions.
Pigmented cysts can mimic pigmented ocular tumors such as malignant melanoma.
Nonpigmented cysts can mimic parasitic cysts such as Cysticercosis, Echinococcus etc.
Complete blood count
Erythrocyte Sedimentation Rate
Serologies for Cysticercosis, Echinoccous, Toxpoplasma gondii, Toxocara canis
Stool examination for ova and cysts
Brain computer tomography
Ocular Investigations:B scan Ultrasonography showing a vitreous cyst with a hyperechogenic wall and acoustically hollow interior with no connections to any part of the eye ie free floating. No scolex seen. Suggestive of a primary floating vitreous cyst. Photo Courtesy- Rajan Eye Care Hospital, Chennai
B Scan Ultrasound to look for scolex in case of cysticercosis
Optical coherence tomography (OCT) can also help characterize the cyst
Ultrasound biomicroscopy (UBM) to rule out anomalies of ciliary body or posterior iris
Fluorescein angiography – assists in characterization of intra and extra cystic vascularization
Observation and follow-up
Laser cystotomy by Argon laser or Nd:Yag laser
Pars plana vitrectomy with cyst excision
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