Retinal Disorders Flashcards
(54 cards)
1
Q
Outer surface attached to
A
Choroid
2
Q
Inner surface attached to
A
Vitreous body
3
Q
Macula
A
- Oval, yellowish area at centre of posterior part
- high concentration of cones
- fovea centralis
4
Q
Optic Disk
A
- 3mm medial to macula
- pierced by central artery of retina
- blind spot
- leaves as optic nerve
5
Q
What are the layers of retina?
A
outermost = retinal pigment epithelium (single layer)
innermost
- ganglion cell layer, axons form optic nerve
- bipolar nerve layer
- photoreceptors (cons & rods)
6
Q
Functions of rods
A
- for night vision
- do not signal wavelength information
7
Q
Function of Cones
A
- for daylight & color vision
- high threshold to light
- concentrated at fovea
8
Q
Symptoms of Macular (central) dysfunction
A
significant visual impairment
- Blurred central vision
- Distorted vision (metamorphopsia)
- Areas of loss of central vision field (scotomata)
9
Q
Distorted vision (metamorphopsia)
A
- micropsia/macropsia
- when photoreceptors gets stretched apart/close together
- straight lines = wavy, bent, irregular
10
Q
Scotomata
A
- areas of loss of central vision field
- if part of photoreceptors layer becomes covered (by blood)
- if photoreceptors gets destroyed
11
Q
Symptoms of peripheral retinal dysfunction
A
- loss of visual field (detected clinically)
- diseases predominantly affecting 1 type of photoreceptors (retinitis pigmentosa & night vision)
12
Q
Age related maculopathy (AMD)
A
Collection of drusen (yellow lesions) in the macula
- overtime undigested lipid product that deposits in Burch’s membrane
13
Q
Dry Form (AMD)
A
Neighboring retinal pigment epithelium & photoreceptors shows degenerative changes
14
Q
Wet/Exudative form (AMD)
A
Angiogenic factors (ex. VEGF) stimulate new vessel formation from choroid through Bruch’s membrane & RPE into sub retinal space -> sub-retinal neovascular membrane
15
Q
Symptoms of AMD
A
- symptoms of macular dysfunction
- progressive, gradual loss of central vision = difficulty reading, recognizing distant objects
- wet form = sudden visual disturbance
16
Q
Signs of AMD
A
- Yellow, well-circumscribed drusen
- Areas of hypo/hyperpigmentation
- Loss of foveal reflex
- Wet = pre-retinal/subretinal hemorrhage
17
Q
Investigations done for AMD
A
- Appearance of retina (through ophthalmoscope)
- Exudative AMD & vision not severely affected = fluorescein angiogram performed to delineate position of sub-retinal neovascular membrane
18
Q
Prognosis for dry AMD
A
- progress very slowly
- increasing difficulty in reading
19
Q
Prognosis of wet AMD
A
- marked deterioration in vision over 3 years (75%)
20
Q
Treatment for Dry AMD
A
- no treatment
- vision magnified with low-vision aids (ex. Magnifier, telescopes)
- reassure peripheral vision won’t get affected
21
Q
Treatment for wet AMD
A
- Argon laser treatment: if membrane is eccentric to fovea
- Photodynamic therapy (PDT): subfoveal membrane
- drugs - anti-VEGF (bevacizumab, ranibizumab) = inhibit angiogenesis
22
Q
Conditions associated with formation of sub-retinal neovascular membranes
A
- AMD
- Myopia
- Pseudoxanthoma elasticum
23
Q
Myopia
A
Loss of central vision (in young adulthood)
24
Q
Pseudoxanthoma elasticum
A
Sub-retinal neovascular membrane grow through elongated cracks in Bruch’s membrane = angioid streaks
25
Pathogenesis of Macular holes
Blunt trauma/idiopathic -> traction by vitreous on thin macular retina -> well-circumscribed hole at center of macular -> loss of acuity
Pre-retinal glial membrane form over macular region -> contraction -> puckering of retina
26
Symptoms of macular holes
Early stages = distortion & mild blurring of vision
27
Treatment of macular holes
Microsurgical vitrectomy technique -> remove membrane -> improve symptoms
28
Macular edema
Accumulation of fluid within retina
29
Diagnosis of macular edema
1. Ophthalmoscopy = loss of normal foveal reflex
2. Confirmatory OCT scan
3. Fluorescein angiogram
30
Causes of macular edema
- Intraocular surgery
- uveitis
- retinal vascular disease (e.g diabetic retinopathy)
- retinitis pigmentosa
31
Treatment for macular edema
1. If its due to uveitis -> give steroids
2. If due to retinitis pigmentosa/following Intraocular surgery -> give acetazolamide
32
Drugs causing macular damages
1. Chloroquine
2. Hydroxychloroquine
3. Phenothiazines
4. Tamoxifen
33
Ophthalmoscopy finding in chloroquine maculopathy
Bull-eye appearance
34
Posterior vitreous detachment
Vitreous gel undergoes degenerative changes in ptn in their 50s and 60s -> detach from retina
35
Symptoms of posterior vitreous detachment
1. Photopsia (flashing lights)
2. Shower of floaters
Most marked on bright days = small pupil throws sharper image on retina
36
Photopsia (flashing lights)
Detaching of vitreous -> traction on retina
37
Shower of floaters
Detaching of vitreous -> ruptures small vessels -> vitreous hemorrhage -> condensations within collapsed vitreous
38
Retinal detachment
Loss of position between the sensory retina & retinal pigment epithelium
39
Rhegmatogenous retinal detachment
Tear/break/hole in retina -> vitreous in sub-retinal space
40
Traction retinal detachment
Retina pulled away from pigment epithelium by contracting fibrous tissue grown on retinal surface
41
Exudative retinal detachment
Fluids in sub-retinal space (e.x tumors)
Without retinal break arising from inflammatory disease of choroid, retinal tumors & retinal angiomatosis
42
Risk factors for rhegmatogenous retinal detachment
- high myopes ptn
- cataract surgery complicated by vitreous loss
- detached retina in other eye
- recent severe eye trauma
43
Tear in sensory retina associated with
- posterior vitreous detachment
- lattice degeneration
44
Symptoms for rhegmatogenous retinal detachment
- progressive development of field defect (shadow/curtain)
- peripheral field loss (early)
- loss of central vision & marked decrease in visual acuity (if macula detached)
- loss of red reflex
45
Signs of rhegmatogenous retinal detachment
1. Ophthalmoscopy = floating, diaphanous membrane (detached retina)
2. Bullous detachment = marked accumulation of fluid in sub-retinal space
3. Tear appears reddish pink (underlying choroidal vessels)
4. Vitreous hemorrhage
46
Treatment for rhegmatogenous retinal detachment
1. Surgery (by cryoprobe/laser) = close causative break & increase attachment
47
Surgeries done for rhegmatogenous retinal detachment
1. External (conventional approach)
2. Internal (vitreoretinal surgery)
48
External (conventional approach)
Relieves vitreous traction
Sclerostomy needed first
49
Internal (vitreoretinal surgery)
Through pars plana
- maintain head posture for several days
- avoid air traveling
50
Prognosis of rhegmatogenous retinal detachment
If surgery is successful -> excellent vision
If macula detached > 24 hrs = acuity not recovered completely, months to restore part of vision
51
Complications in rhegmatogenous retinal detachment surgery
Fibrotic changes in vitreous (proliferative vitreoretinopathy) -> traction on retina & further detachment
52
Traction retinal detachment seen in?
- proliferative diabetic retinopathy
- proliferative vitreoretinopathy
- vitreoretinal surgery
53
Exudative retinal detachment seen in
- posterior uveitis
- Intraocular tumors
- toxemia of pregnancy
- central serous retinopathy affecting macula
54
Retinoschisis
Degenerative splitting of retina with cyst formation between the 2 layers
