The Lens Opacities Classification System II (LOCS II) is a method of reproducibly evaluating age-related cataracts. It involves grading 4 features of the cataract by comparing the features seen against a standard set of transparencies. It is an extension of the LOCS I system, with an expanded number of photographic standards and the use of color rather than black and white for the images. The LOCS II does not use a measure of visual acuity since this is inconsistently correlated with the degree of cataract formation and may be affected by other eye disorders.
Parameters graded:
(1) nuclear color (NC)
(2) nuclear opalescence (N)
(3) cortical cataract (C)
(4) posterior subcapsular (P)
The grading requires a slit-lamp examination.
Parameter
Features
Grade
nuclear color (NC)
The color of the posterior cortical/posterior subcapsular reflex is:
< NI standard
NC0
similar to the NI standard
NC1
> NI standard
NC2
nuclear opalescence (N)
The average opalescence of the nucleus is:
<= that in N0
N0
> N0 but <= NI
NI
> NI but <= NII
NII
> NII but <= NIII
NIII
> NIII
NIV
cortical cataract (C)
The aggregate extent of linearly organized or clustered opacities is:
<= that in C0
C0
> C0 but <= Ctr (trace)
Ctr
> Ctr but <= CI
CI
> CI but <= CII
CII
> CII but <= CIII
CIII
> CIII but <= CIV
CIV
> CIV
CV
posterior subcapsular (P)
The aggregate extent of the axial opacity seen in retro-illumination is:
<= that in P0
P0
> P0 but <= PI
PI
> PI but <= PII
PII
> PII but <= PIII
PIII
> PIII
PIV
after Table I, page 995.
where:
• Nuclear color is graded by comparing the color of the posterior cortical/posterior subcapsular reflex to the NI standard.
Nuclear Standard
Description
N0
clear nucleus
NI
early degree of nuclear opacification
NII
moderately advanced nuclear opacification
NIII
advanced nuclear opacification and browning
Cortical Standard
Description
C0
clear lens devoid of aggregated dots, flecks, vacuoles and waterclefts
Ctr
minimal degree of cortical opacification and/or minispoke formation
CI
more extensive opacification with small minispokes
CII
cortical spoking that obscures more than 2 full quadrants
CIII
opacification that obscures about 50% of the intrapupillary zone
CIV
advanced opacification filling about 90% of the intrapupillary zone
Posterior Subcapsular Standard
Description
P0
clear posterior capsule
PI
cataract filling about 3% of the area of the posterior capsule
PII
about 30% opacification of the area of the posterior capsule
PIII
about 50% opacification of the area of the posterior capsule
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