10

MANUAL

OF RETINAL

SURGERY

examiner

should consider whether

the configuration

of the detachment

is consistent

with

the' location

of

the retinal

breaks.

Retinal detachments

accumulate

subretinal

fluid

in a predictable

manner around

the

retinal

break

of origin.

These

observations

have

been extensively

described

and

are known

as Lin-

coff's Rules. The

shape

of

the

retinal

detachment

indicates

the location

of

the

break

in 96%

of cases.

Some

concepts

that may

be useful

in finding

the

break

are

that (1)

in superonasal

or temporal

retinal

detachments, the

retinal

break

lies within

one

and

one-half

clock

hours

of

the

highest

border

98% of

the time;

(2) in superior

detachments

that

cross

the

midline,

the primary

retinal

break

is at 12 o'clock

or within

a triangle

the

apex

of

which is

at

the

ora

serrata

and

that

intersects

the

equator

I

hour to

either

side

of

12 o'clock,

this

is present

93% of the

time;

(3)

in inferior

detachments,

the higher

side

indicates

to which side

of the

60 'clock

meridian

an

inferior hole

lies

95% of the time;

(4) when

an infe-

rior retinal

detachment

has

a bullous

configuration,

the primary

hole

lies above

the

horizontal

meridian.

These

rules are most

applicable

in the

absence

of proliferative

vitreoretinopathy

since significant

tractional

forces

can alter the

distribution

of sub-

retinal fluid. If

the

location

of

the retinal

breaks

does not

explain

the retinal

detachment,

additional

study

of the

retinal

detachment

is suggested

to seck

any

possible

missed

retinal

breaks.

Preoperative

Informed

Consent

The patient

with retinal detachment

is often quite

apprehensive,

for

several reasons.

The acute dis-

covery of a retinal

detachment

has

brought

the reti-

nal surgeon

and the patient

together. Usually the

patient has

not met

the retinal

surgeon until referred

for evaluation

of retinal

detachment.

Often

patients

have a poor

understanding of

the pathophysiologic

processes

involved

in

retinal

detachment

and the

surgical

procedure required

for

treatment.

There-

fore,

an explanation

should

be

provided

to

the

patient

of the events

leading to

the

retinal

detach-

ment

and the planned

treatment.

The overall

tone

should

be supportive

and positive

since the progno-

sis for

retinal reattachment

is

good. The

patient

should

be informed

of possible

intraoperative

as

well as postoperative

complications. These

include

complications

from

drainage of

subretinal

fluid,

retinal perforation

during placement

of

scleral

sutures,

choroidal

detachment,

macular pucker,

pro-

liferative vitreoretinopathy,

or diplopia.

If the

mac-

ula

is

detached

preoperatively,

the prognosis

for

return

of central

vision

should

be

indicated

to the

patient.

Patients

may

not realize

that it may

take

up

to 6 months

before

central

vision

returns.

Finally,

the patient

should be given

ample

opportunity

to

ask

any questions

related

to the

planned

surgery.

Beyer NE. The

Peripheral Retina

in Profile: A Stereoscopic

Atlas, Torrance.

CA: Criterion Press;

1'.182.

Beyer NE. Peripheral

retinal

lesions related to rhcgmatllge-

nous retinal detachment.

In: Guyer DR. Yannuzzi LA.

Chang S. Shields

JA. Green

WR. cds, Re/illa·I/i/reous

Macula. Vol.

2.

Philadelphia:

Saunders;

1999:

1219-1247.

Brod RD. Lightman

DA. Packer

AJ. Saras HP. Correlation

bel ween

vitreous

pigment granules

and retinal

breaks

in eyes with

acute

posterior

vitreous

detachment.

Oph-

thulmology 1991 ;98: 1366-1369.

Hilton GF. McLean

EB, Brinton

DA. Retinal Detactnncnt:

Principles

and

Practice,

2nd ed. San Francisco:

Amer-

ican Academy

of Ophthalmology:

1995:41-81.

Lincoff H. Gieser R. Finding

the retinal

hole. Arch

Opluhal-

mo/1971;85:565.

Retinol

Derachmcnt : Diag-

Regillo

CD,

Benson

WE.

nosis and Management.

3rd ed. Philadelphia:

Lippin-

colt-Raven;

1998:45-99.

Schepens

CLS. Retinal

Detachment

and Allied

Diseases.

Philadelphia:

Saunders;

1983:99-232.

Ophthalmic

echography

and electrophysiologic

stud-

ies can provide

valuable

aid to

today's vitreoretinal

surgeon

in the evaluation

of eyes

with opaque

media.

Obviously,

in eyes

with

a rhegrnatogenous

retinal

detachment

and clear media. no ancillary

testing

is

needed

for diagnosis

and treatment. In contrast.

an eye

with a dense

cataract.

cyclitic membrane,

hyphcrna,

vitreous

hemorrhage.

or other significant

opacity

of

the media

may harbor

posterior

segment

pathology

such as

a tumor or detachment

that can

readily

be

diagnosed

with preoperative echography.

Ophthalmic

echography

has emerged

as a diagnostic

modality

that

is extremely

useful

in the assessment

of

eyes with

anterior

or posterior

segment media opacity.

Electro-

physiology

may also be of use in the functional

assess-

ment of eyes

with cloudy

media

to determine

if there

i.~a reasonable

prospect of salvaging vision.

The! development

of clinical

ophthalmic

echogra-

phy in the 1970s greatly

modified

and improved

the

management

of retinal

detachments

and

other

pos-

terior segment

pathology

in eyes

with

opaque

media. The

concurrent introduction

of

pars

plana

vitrectomy

by Robert

Macherner

gave

the

retinal

surgeon the

necessary

tools

to approach

such eyes

~Iggressively

and, in many cases,

to effect

dramatic

visual restoration.

Prior to the advent

of pars plana

vitrcctomy,

the management

of retinal

detachment

in the presence

of vitreous

hemorrhage

typically

included

bed rest. elevation

of

the head. and bilat-

eral

eye

patching. If

the blood

cleared

in

a

timely

fashion,

retinal tears

could be localized

and

scleral

buckling

performed.

Eyes in

which the

vitreous

hemorrhage

did not

clear

or

did not

clear

ade-

quately

to

allow for

visualization

of

the

retinal

breaks might

be subjected

to

a so-called

"blind"

buckling

procedure. Certainly.

the advent

of

vitrcc-

torny and

subsequent

advances

in

v itreoret

inal

surgery

have

allowed

for earlier

and

more

precise

intervention

in these

cases.

In

an eye

with

media

opacities

that preclude

visualization

of

the

fundus.

echography

can quickly

answer

a number

of ques-

tions of

interest

to the

vitreoretinal

surgeon

and

facilitate

appropriate

management.

I.

Is the

posterior segment

anatomically

normal')

2.

Is the

retina detached?

Is

there

evidence

of pro-

liferative

vitreoretinopathy

(PVR)?

Is

there evi-

dence

of tractional

retinal detachment?

3.

Are

there ultrasonographic

findings

that

suggest

a secondary

retinal

detachment

(tumor,

inflam-

matory condition)?

4.

Are

choroidal

detachments

(serous

or

hemor-

rhagic) present?

5. Are

signs

of

trauma

evident,

such

as subretinal

hemorrhage,

posterior

rupture,

intraocular

for-

eign

body. or lens

luxation

or disruption?

6.

Is there

an occult

posterior

tumor present,

and

if

so, what are its characteristics?

Contact

Bvscan

echography

is the method

of

choice

for

the vitreoretinal

surgeon

evaluating

eyes

12

MANUAL

OF RETINAL

SURGERY

with

cloudy

media.

Real-time

dynamic

Bvscun

echography

can yield

valuable information

regard-

ing the nature

of a retinal

detachment,

allowing

for

the differentiation

of a mobile,

more

acute

detach-

ment from

a fixed.

chronic

one.

Currently,

three-

dimensional ultrasound

imaging

is being

evaluated

for clinical

application.

Possible

uses

of

three-

dimensional ultrasound

include volumetric

analysis

of tumors

and

more accurate

assessment

of

com-

plex retinal (Jetachlllents.

A-scan techniques.

particularly standardized A-

scan

echography

as popularized

by

Karl Ossoinig,

are invaluable

for

determining

the size

and

charac-

teristics of

intraocular

tumors. Such procedures

can

accurately

assess

the

apical

height

of a tumor

and

often provide

useful

tissue characterization.

For

example.

a homogenous

tumor

mass

such

as a pos-

terior uveal melanoma

would display

low

internal

reflectivity

on

A-scan.

whereas

a vascular

tumor

such

as

a choroidal

hemangioma

would

typically

show a high internal

reflectivity

pattern

due to its

heterogeneous tissue

structure.

Normal

Posterior

Segment

If the posterior

segment

is anatomically

normal.

the

vitreous

cavity

",..ill

be

acoustically

clear

or

have

Rhegmatogenous

Retinal

Detachment

Total retinal

detachment

is usually

a

straightfor-

ward diagnosis

with

echography.

Highly reflective

retinal

leaves

emanate

from

the

optic nerve

head

and rejoin

the

globe

wall

anteriorly

at

the

ora ser-

rata.

Bullous

detachments

are

widely separated

from

the eye

wall and have

a convex configuration.

In contrast,

a shallow

retinal

detachment

may

remain

close

to the

eye

wall and

be difficult

to dis-

tinguish from

other

entities.

A partial

retinal

detachment

is not hard

to identify

if the detachment

extends

back

to the optic

nerve

head.

A localized

detachment

in the

periphery,

however.

may

some-

times

be difficult

to differentiate

from a

vitreous

membrane.

Detached

retina

is

normally

more

reflective

or

echogenic

<brighter on B-scan)

than

are vitreous

membranes. Figure

3-1 shows

an eye

with vitreous

hemorrhage

and

a localized

retinal

detachment.

In

this particular

echogram,

one can

also

visualize

the

retinal

break

(arrow).

There is