Download lattice degeneration:pathophysiology

Vitreoretinal Considerations in Rhegmatogenous Retinal Detachment
Jeffrey S. Nyman, O.D., F.A.A.O.
Associate Professor
Pennsylvania College of Optometry
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INTRODUCTION AND OVERVIEW
Nontraumatic RRD occurs in about 1 in 10000 persons per year (incidence = .01%)
o Even higher in pseudophakes (approx. 1-3%)
o Most common potential cause of blindness after cataract surgery
Pathogenesis consists of vitreous syneresis leading to vitreous detachment leading to traction with
formation of retinal breaks allowing intraocular fluid currents to separate the neurosensory retina
from the RPE (retinal detachment)
Certain degenerative peripheral retinal degenerations can lead to retinal breaks, predisposing the
patient to retinal detachment – this discussion will review these conditions
POSTERIOR VITREOUS DETACHMENT
 SYMPTOMS: sudden onset of flashes and floaters (“fly”), shower of dust (“cobwebs”)
 careful history to let patient describe exact nature of the floaters and flashes, and any other
associated visual disturbances (localized blur; red vision, etc.)
 EPIDEMIOLOGY:
 high incidence in aphakes (80 - 93%); incidence increases with age (27% between ages 60 - 69;
63% over age 70), and axial length (myopia)
10 -15% have retinal breaks
70% incidence of breaks when hem. present
2 - 4% incidence of breaks when no hem.
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PVD - PATHOGENESIS
vitreous syneresis (liquefaction)
cavities form, coalesce, and move to posterior vitreous
 Hole eventually forms in the posterior vitreous which allows liquefied vitreous to rush into
the retrovitreal space, rapidly separating the posterior hyaloid from the retina
 PVD - EXAMINATION
 BIO + slit lamp biomicroscopy and fundus contact lens examination
optically empty space between posterior hyaloid and retina
annular opacity (Weiss ring) - may be partial or whole
may see the opacity with direct ophthalmoscopy
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 Shaeffer ‘s sign - highly suggestive of RRD (“tobacco dust” in vitreous of phakic eye)
 May see VH - sign of tear
 Vision threatening complications of acute PVD are dependent upon strength and extent of
pre-existing vitreoretinal adhesions
 Retinal tears occur in about 10 – 15% of cases at sites of strong vitreoretinal adhesions,
including WsP, lattice degen., FPP, strong paravascular attachments, and cystic retinal tufts
PVD - COMPLICATIONS
 Retinal tear formation and vitreous hemorrhage
 May lead to RRD
LATTICE DEGENERATION
many synonyms for this condition
Def’n: a sharply demarcated, circumferentially oriented disease process located at or anterior to the
equator and characterized by:
–retinal thinning
–adjacent vitreous abnormalities
Byer: Surv. Ophthal 23(4), 1979: “If, with indirect ophthalmoscopy and scleral indentation, the
examiner can demonstrate at the borders of such a lesion an abrupt, discrete irregularity of the otherwise
smooth surface of the retina, the lesion should be regarded as lattice deg., in spite of variations in
pigmentation or other morphologic features.”
LATTICE DEGENERATION : VITREOUS ABNORMALITIES
vitreous liquefaction or absence of recognizable vitreous (lacuna) overlying area of thinned
retina
vitreous condensation and exaggerated vitreoretinal attachments at the borders of the lesion
splitting of the vitreous cortex, allowing communication with the semi-fluid central vitreous
LATTICE DEGENERATION: CLINICAL FEATURES
tends to occur more frequently in the upper periphery, more temporally than nasally
usually near the equator with long axis parallel to the ora serrata; may be radially oriented
may appear oriented along a peripheral retinal vessel
variable configuration and size; most are oval or elongated islands
dimensions vary fom 0.5 to 1.5 DD in width and from 1 to 12 DD in len gth
LATTICE DEGENERATION: MORPHOLOGIC FEATURES
localized retinal thinning (100% of cases)
pigmentation (80 -90% of cases)
whitish-yellow surface flecks (80%)
round, oval, or linear white patches
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round, oval, or linear red craters
small, atrophic round holes (18 - 29%)
branching white lines (12%)
yellow atrophic spots
tractional tears @ posterior margin (1.5 -2.5%)
LATTICE DEGENERATION: EPIDEMIOLOGY/HEREDITYPREVALENCE
 Byer: 8% of 1700 pts.
 Straatsma - 10.7% of 800 autopsy eyes
 maximum incidence in first decade
 no racial or sexual predilection
 often bilateral
 HEREDITY
 few heredity studies on lattice
 probable autosomal dominant transmission
LATTICE DEGENERATION: CLINICAL COURSE
slowly progressive
becomes evident in second decade and evolves slowly thereafter
early lesions show mild retinal changes, discrete and spindle shaped, with minimal pigmentation
changes are due to loss of retinal transparency and appear like isolated areas of white without pressure
advanced lesions show severe retinal and vitreous changes
lesions are broad and long and have white crosshatched lines that are continuous with the retinal vessels
(lattice lines)
pigment clumping and atrophy
middle part of lesion extremely thin and may contain punched out areas as a result of incomplete or
complete retinal holes
LATTICE DEGENERATION:PATHOPHYSIOLOGY
Pathogenesis obscure (4 theories):
1. vitreous disease is primary cause of retinal changes
2. ischemic retinovascular disease causes local- ized hypoxia and secondarily affects the vitreous
3. liquefied vitreous has a degenerative effect on normal retina
4. based primarily on genetic and developmental factors
LATTICE DEGENERATION: PROGNOSIS
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eyes with lattice are prone to get retinal breaks
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lattice associated with holes in 18.2% of cases; tears are present in 1.4% of cases
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patients with rheg. RD, the percentage who have lattice ranges from 20 -37%
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RD more likely to develop in eyes with tears than in those with holes
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rhegmatogenous RD resulting from breaks in extensive areas of lattice tend to have a poorer
prognosis, especially in cases with no PVD
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Relationship to vitreous base :
Potential for a lattice lesion to develop a tractional tear at the time of a PVD depends upon its precise
relationship to the vitreous base
Foos (1974) classified tears as extrabasal, juxtabasal, or intrabasal
juxtabasal tears carry greatest risk of RD
not all flap tears in eyes with lattice are adjacent to the lattice lesion
LATTICE DEGENERATION: TREATMENT CONSIDERATIONS
lattice itself does not interfere with visual function
need for treatment controversial
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prophylactic treatment is indicated when:
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lattice with tractional tears at edge *
lattice with holes, especially when symptomatic, or where hole is
surrounded by SRF, associated with high myopia, or strong family Hx
of RD
observable progression with development of subretinal fluid
cataract obscuring view
aphakia or about to be aphakic
fellow eye with RD
lattice in only seeing eye
ACQUIRED RETINOSCHISIS
in early stages appears as an exaggeration of cystoid degen., affecting the extreme periphery most often
inferotemporally
characterized by disruption of radial pillars and complete separation of inner and outer layers
appears as a flat, smooth elevation of the retina
in advanced stage it forms a smooth, transparent, sharply demarcated, immobile cyst-like elevation
convex border always faces posterior pole
present in about 1 - 2% of people over age 20
inner layer contains blood vessels with white or copper-wire appearance
occasionally, inner surface contains grey-white flecks resembling snowflakes
outer layer difficult to visualize, but scleral depression may give a ‘white with pressure’ or beaten metal
appearance
always separated from ora by narrow band of cystoid degeneration
TYPES OF RETINOSCHISIS
TYPICAL
round or ovoid area of retinal splitting
strong predilection for inferior temporal quadrant
smooth fusiform elevation of inner layer surrounded on all sides by cystoid degen. and retinal pillars
prominent broken pillars near margin
central portion has thin inner wall consisting of ILM, NFL and retinal vessels
RETICULAR
even more extensive tissue loss and thinning of inner and outer layers
band of typical cystoid degen. separates the schisis from the ora
round or ovoid shape with bullous elevation of extremely thin inner layer and an irregular pitted outer
layer, giving it a pocked or honeycomb appearance
inner layer extremely thin, with blood vessels giving it an arborizing reticular pattern
Round or ovoid outer layer holes with rolled posterior edges are found more frequently than inner layer
holes, especially near posterior margin
o this associaton with outer layer breaks may lead to rhegmatogenous R.D.
Rhegmatogenous R.D
RETINOSCHISIS : DIFFERENTIAL Dx
o appears rippled compared to smooth surface of schisis; less transparent
o relative field defect in R.D., absolute defect in schisis
Choroidal melanoma
o in schisis have transparent inner wall with preservation of underlying choroidal pattern
o may need B-scan to detect melanoma
White without pressure
o flat lesion with geographic borders
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RETINOSCHISIS: COMPLICATIONS
 Retinal detachment
 originates from outer layer holes
 slowly progressive
 Progression toward posterior pole
 will get absolute field defect when anterior to equator
 rarely extends through the fovea
 Hemorrhage
RETINOSCHISIS: MANAGEMENT
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Prognosis generally excellent with no visual impairment in most cases
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Treatment only indicated when:
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schisis is progressive and threatens macula
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schisis and associated nonrhegmatogenous RD are progressive and threaten
macula
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retinal breaks in both layers are associated with progressive, symptomatic
RRD
DEVELOPMENTAL VITREORETINAL VARIATIONS ASSOCIATED WITH RETINAL
BREAKS
ENCLOSED ORAL BAYS
 Retinal tear in 16.7% of cases with PVD
MERIDIONAL FOLDS AND COMPLEXES
 Radially aligned elevated folds of peripheral retina
 Runs posteriorly from ora
 Upper nasal quadrant most often
 20% prevalence
o Retinal break may occur due to increased traction in meridian
CYSTIC RETINAL TUFTS
 extrabasal location
 larger than non-cystic tufts
 nodular projection of retinal tissue that extends from a vitreous attachment at the apex to a
base that ranges from 0.1-1.0 mm
 surrounded by cystic retinal degen.
 often have pigment at base (focal pigment proliferation) trophic changes may be present in
immediately adjacent retina
 may account for up to 10% of RRDs
 synonyms:
 granular patch, globule, congenital rosette
 clinically important because they may be avulsed by vitreous traction with or without PVDin
the larger lesions, this results in a full thickness retinal break
 present at birth and evident in 5% of adults
 no quadrant predilection
 Foos’ autopsy study found that cystic tufts accounted for 36% of postoral tractional tears, and
that they occurred in the extrabasal zone
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CYSTIC RETINAL TUFTS: MANAGEMENT
 Byer calculated a low risk of retinal detachment (less than 1% - in the range between 0.18% 0.28%)
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Because of the relatively high prevalence (5%) and the low risk of an ensuing detachment,
prophylactic treatment is not necessary
VITREORETINAL ATTACHMENTS: ZONULAR TRACTION TUFT
always projects from the retinal surface internally and anteriorly toward the zonule
usually isolated and located within the vitreous base, they are joined to zonular fibers at the apex; most
frequent in nasal quadrants
vary in length and are associated with trophic and tractional alterations on the retinal end
can cause small round retinal holes
present @ birth and found in 15% of patients
RETINAL BREAKS
CLASSIFICATION
atrophic retinal hole
operculated tear
horseshoe tear
retinal dialysis
RETINAL HOLES
most (76%) holes are secondary to lattice degeneration
a hole is a retinal break not caused by traction
those unrelated to lattice degen. or other disorders are rounded, full thickness breaks without a flap or
free operculum
usually located anteriorly within vitreous base, holes have smooth margins, normal appearing adjacent
retina, and vitreous attachments are not unusual
present in approximately 4% of adults
no quadrant predilection
scleral depression helps differentiate from retinal hemorrhage
hole develops changing red color while hemorrhage remains stable
most do not lead to RD (< 1% ); but if located posterior to vitreous base, more likely to do so
OPERCULATED TEARS
a tear is a retinal break that is secondary to traction
may see free-floating operculum
retains its attachment to the vitreous
almost always located anterior to the tear
if you see blood in vitreous, it indicates a fresh tear
16% chance of RD if acute (“fresh”)
HORSHESHOE -SHAPED TEARS (FLAP TEARS)
poorest prognosis (50% chance of RD if acute)
tear is U or V shaped with the broad base directed anteriorly
tapered flap extends into the vitreous, and always faces the posterior pole
tears unassociated with predisposing retinal abnormalities are likely to occur at sites of exaggerated
paravascular traction and along the vitreous base ; occur as a result of PVD
RETINAL DIALYSIS
an anterior retinal dialysis is a retinal tear which occurs at the ora serrata
concentric disinsertion of sensory retina from non-pigmented pars plana epithelium
occur post-traumatically or spontaneously in young people
frequently asymptomatic and associated with a slowly progressive RD
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–pigment demarcation lines and intraretinal macrocysts are common in these cases
Traumatic
typically involves superonasal quadrant
usually unilateral
may be vitreous hem. or other signs of ocular trauma
Spontaneous
usually involves inferotemporal quadrant
normally associated with slowly progressive RD
tend to be asymptomatic even when associated with RD
found in about 10% of patients with RD
patients generally young and emmetropic
males more frequently than females
multiple dialyses may occur in one eye
may present bilaterally, implying a congenital retinal frailty
RETINAL BREAKS: TREATMENT CONSIDERATIONS
about 6% of eyes have a break, but only one person per 10 to 15000 develops an RD
prophylactic surgery indicated when risk/benefit ratio justifies it
no long term randomized, controlled trials
risk of RRD based on analysis of:
(1) characteristics of the specific ocular condition
(2) associated ocular and systemic findings (eg. myopia, S/P cataract surgery, Marfan’s
syndrome; strong family Hx of RD)
(3) status of fellow eye (Hx of RD)
strong indications for treatment:
recent onset of flashes and floaters
hemorrhage associated with the break
moderate traction on edges of tear
presence of subretinal fluid
Hx of RD in fellow eye
hereditary condition (Stickler’s, Marfan)
retinal dialysis
treatment goal: production of an adhesive chorioretinal scar binding sensory retina to RPE
treatment technology:
laser photocoagulation
cryotherapy
treatment effectiveness:
treatment of symptomatic tractional tears significantly reduces risk of RD
RETINAL BREAKS: TREATMENT COMPLICATIONS
creation of new retinal breaks
extension of retinal tear and iatrogenic RD
epiretinal membrane formation with contraction (macular pucker)
o numerous reports indicate postoperative occurrence to be 0% - 2.2% of cases
o may be due to the PVD which caused the tear
complications of anesthesia
o minimized by avoiding retrobulbar anesthesia
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RETINAL DETACHMENT: CLASSIFICATION
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Def’n: RD is a complex and varied disorder in which there is separation of the sensory retina and the
retinal pigment epithelium
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Types:
o RHEGMATOGENOUS -associated with a break
o TRACTIONAL - retina is pulled off - no break
o EXUDATIVE - serous elevation of the retina with shifting fluid
RHEGMATOGENOUS RETINAL DETACHMENT (RRD)
o Pathophysiology
 results from complicated interaction of vitreous body, RPE, and other ocular tissues
 usually follows PVD with traction exerted on the retina, and resultant tears at sites of
predisposed areas
 tears allow for passage of fluid into the subretinal space (RRD)
o RRD - CLINICAL FINDINGS
 50% of patients with RRD have photopsia or floaters
 IOP is usually lower in affected eye, but may be higher in some longstanding
detachments
 Shafer’s sign (“tobacco dust”) - clumped pigment in vitreous or ant. seg.
 may see subtle bullous or shallow retinal elevation with translucent retina, darker
appearing vessels, and obscuration of choroidal details
 detached retina has a corrugated appearance, especially in recent RD, and undulates with
eye movements
 Fixed folds almost always indicate RRD
 RRD - ULTRASONOGRAPHY
o B-scan ultrasonography valuable in establishing the diagnosis
 especially in cases where fundus is difficult to visualize by standard
techniques
 can also help differentially diagnose other lesions, eg., underlying choroidal tumors
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RRD - TREATMENT
o the principles of RD surgery are :
 first, find all breaks
 then, treat all breaks
o if vitreous traction on the breaks is present, it must be released
 usually by scleral buckle
 occasionally by vitrectomy
o if all breaks are closed, the subretinal fluid will be absorbed
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