Lattice Degeneration

Lattice degeneration is a common, atrophic disease of the peripheral retina characterized by oval or linear patches of retinal thinning.[1, 2] The prevalence peaks by the second decade and is believed to be minimally progressive but may be complicated by retinal breaks and retinal detachment.[3]

The pathogenesis of lattice degeneration is not well understood, although several theories have been proposed.[4] Regional maldevelopment or absence of the internal limiting membrane versus abnormal vitreoretinal traction dynamics appear to be the most cogent arguments proposed.

Frequency

United States

Lattice degeneration affects approximately 10% of the population and is bilateral in 30-50% of patients who are affected. A variable familial risk may be present on the basis of various autosomal dominant pedigrees.[5] An increased prevalence exists in myopic eyes, and its prevalence may be associated with increasing axial length, reaching 15% in the longest eyes.

International

No information is available regarding the international occurrence of lattice degeneration.

Mortality/Morbidity

See discussion of retinal detachment in History and Physical.

Race

No reported racial differences exist in lattice degeneration.

Sex

No reported sex differences exist in lattice degeneration.

Age

See History regarding early onset and progression with age.

The prognosis of lattice degeneration is generally good.

Educate the patient on signs of retinal detachment.

Encourage annual follow-up for dilated eye examinations.

Patients with lattice degeneration need to be made aware of their condition and should be warned about the increased lifetime risk of retinal tears or detachment. They should be advised to see an eye doctor immediately if they develop symptoms of retinal tears or detachments, including new floaters, flashes of light, decreasing vision, or a "curtain" in their vision.

Patients with lattice degeneration are typically asymptomatic, and the lesions are usually an incidental finding of dilated ophthalmologic examination. A presenting complaint of blurriness in the distance may be the result of myopia, a common association with lattice degeneration. The acute onset of floaters, flashes of light, peripheral field loss, or central vision loss may indicate the presence of a retinal tear or detachment, a complication of lattice lesions.[6]

Clinical features

Lattice degeneration is characterized by oval or linear patches of atrophic retina with a reddish base and is variably located within the equatorial region of the fundus, typically inferotemporal.[2]

Lesions may be isolated or multifocal, variable in dimension, and usually are oriented concentric or slightly oblique to the ora serrata.

Condensed vitreous at the margins of the lattice lesions may appear as vitreous opacities and represent regions of increased vitreoretinal adhesion; overlying vitreal opacities alternatively may be explained by glial proliferation.[7]

Crisscrossing fine white lines that account for the name lattice degeneration are present in roughly only 10% of lesions and most likely represent hyalinized blood vessels; this is shown in the image below.

Various pigmentary disturbances, shown in the image below, occur in more than 80% of lattice lesions. White-yellow occasionally refractile flecks, similar to that seen with degenerative retinoschisis, are an additional common associated feature.

Atrophic retinal holes, shown in the image below, and tractional retinal tears may complicate lattice degeneration and increase the risk of retinal detachment.

Clinical variations

Snail-track degeneration is a morphologic descriptive term for retinal lesions with the same characteristic size, shape, orientation, and location as lattice lesions and is associated with the aforementioned yellowish flecks. Examples of snail-track degeneration are shown in the images below.

Vitreous base excavations represent lesions of similar shape, size, and orientations as lattice lesions having a uniform reddish base and located within the vitreous base.

Pigmentary degeneration is a term that most likely represents lattice lesions with prominent but variable pigmentary changes, including clumps of pigment sometimes heavily scattered at the base of lattice lesions and demarcation lines circumscribing cuffs of subretinal fluid.

When retinal thinning and pigmentary disturbances are found along retinal vessels, these lattice lesions are referred to as radial perivascular chorioretinal degeneration and are classic findings in Wagner and Stickler disease, a familial vitreoretinal degenerative syndrome. An example of this is shown in the image below.

Clinical examination

Identification of lattice lesions depends largely upon the experience of the examiner and the method of examination used.

In patients with symptomatic lattice degeneration (presence of newly onset flashes or floaters), the retinal periphery must be viewed for 360° of its circumference to identify any retinal breaks, if present. If the general ophthalmologist is unable to do so, referral should be promptly made to a vitreoretinal subspecialist.

The most convenient and frequently used method of examination to detect lattice is with binocular indirect ophthalmoscopy with scleral depression (indentation).

Slit lamp examination with a Goldmann contact lens is used less frequently. This method allows for high magnification of the lattice lesions and the associated vitreoretinal relationships, but evaluation with scleral depression, a critical element of the peripheral examination, becomes technically difficult when using a contact lens.

Clinical course

Lattice lesions are believed to develop early in one's lifetime with minimal progression thereafter. Associated features, such as crisscrossing sclerotic vessels, pigmentation, and atrophic retinal holes, may subsequently develop.

Retinal detachment is a relatively rare complication of lattice degeneration (< 1% of patients with lattice degeneration), but lattice degeneration is associated with as many as 40% of all rhegmatogenous retinal detachments. Lattice degeneration is present in 11% of fellow eyes in patients with rhegmatogenous retinal detachments.[8, 9, 10] Rhegmatogenous retinal detachment is shown in the image below.

A 2015 study reported a higher risk (3.4%) of retinal tears and detachments in myopic eyes (>6 D) over a 10-year period.[11]

Retinal detachments caused by lattice degeneration occur most commonly by a tractional tear at the cuff or posterior margin of the lattice lesion or less commonly by means of an atrophic hole within the zone of lattice.

Tractional tears

Tractional tears located at the margin of lattice account for 55-70% of retinal detachments in lattice degeneration and are the result of a posterior vitreous detachment (PVD).

These patients are typically older than 50 years, and only 40% of such eyes are myopic.

An acute PVD complicated by retinal tear formation usually is signaled by the complaint of new-onset floaters and/or flashing lights (referred to as photopsia)

As in all retinal tears, preretinal or vitreous hemorrhage may be present if the tear extends through peripheral retinal blood vessel.

Patients with these complaints constitute a true ophthalmologic emergency and need urgent ophthalmic examination.

PVD-related lattice detachments typically are superotemporal and not associated with demarcation lines. Surgical repair is anatomically successful in 90% of such cases.

Atrophic holes

Atrophic holes account for 30-45% of retinal detachments associated with lattice degeneration. In another retrospective case-controlled study, 23.6% of patients with retinal detachments had atrophic holes associated with lattice degeneration.[12]

Seventy percent of patients with rhegmatogenous retinal detachment secondary to round atrophic holes in lattice degeneration occur in patients younger than 40 years, and 70% of these detachments occur in myopic eyes. Sixty percent are found in females.

Fellow eye pathology is found in a significant (96%) portion of these patients. Thus, examination of the fellow eye is important in these cases.

The posterior hyaloid gel usually is attached, excluding a PVD-related mechanism. These detachments are typically inferior, occur slowly, and demonstrate demarcation lines on examination resulting from the slow progressive accumulation of subretinal fluid.

A 98-100% success rate exists in repairing such inferior retinal detachments with demarcation lines with an excellent visual prognosis in the absence of macular detachment.

See Pathophysiology.

A 360° evaluation of the peripheral retina is conducted using scleral depression or the Goldmann 3-mirror lens. 

Potential complications of lattice degeneration include development of retinal breaks or detachments.

A dilated eye examination with careful examination of the peripheral retina may be performed.

No appropriate laboratory studies exist for lattice degeneration.

Optos camera fundus photography may be useful for annual follow-up and documentation of the condition.

Examination by direct and indirect ophthalmoscopy

Histologic studies of autopsy cases demonstrate that lattice lesions are characterized by 3 invariable features: thinning or atrophy of the inner retinal layers, vitreous liquefaction overlying the area of thinned retina, and vitreous condensation and exaggerated vitreoretinal attachments at the borders of the lesions.

The blood vessels within the lesions are usually patent, but they often show fibrous thickening of their walls, which correlates to the white lattice lines seen clinically. Melanin-laden macrophages may explain the pigmentation seen clinically. Glial proliferations may represent overlying preretinal opacities.

Electron microscopic studies have demonstrated retinal thinning, loss of retinal neurons, internal limiting lamina absence, fibrosis of blood vessels, and accumulation of pigment and/or glial elements.

The presence of uncomplicated lattice does not interfere with visual function and does not constitute a high risk for future development of retinal detachment. Prophylactic treatment is clearly indicated only in the context of specific circumstances.[13, 14, 15]

Indications for prophylactic treatment

Lattice degeneration complicated by tractional tears as the result of an acute, symptomatic posterior vitreous detachment represents a high-risk situation for future retinal detachment and is an urgent indication for laser retinopexy. Lattice and atrophic holes complicated by progressively increasing subretinal fluid represents an additional indication for surgical intervention.

The presence of lattice lesions in fellow eyes of patients who have sustained retinal detachment in the first eye may be treated prophylactically. Exceptions may include eyes with greater than 6 clock hours of lattice lesions and eyes with myopia greater than 6 diopters (D). Strong evidence suggests that subsequent retinal detachments may occur as a result of lesions developing in previously healthy retina.[16] Moreover, laser scars may increase vitreoretinal adhesion and increase the risk of future retinal tears. Therefore, this indication is controversial. In the absence of the aforementioned features, convincing evidence does not exist to clearly indicate prophylactic laser treatment of fellow eye lattice lesions.

Although prophylactic laser treatment may not convincingly prevent subsequent retinal detachment, some authors believe that laser demarcation may limit the extent of future detachments and help preserve the macula.

Methods of prophylactic treatment

Subclinical retinal detachment (>1-disc diameter of subretinal fluid but < 2-disc diameters posterior to the equator) may be treated more effectively with a scleral buckle approach versus a laser barrier. 

Laser photocoagulation is the primary method of prophylactic treatment. Recommended laser settings include the following: green, yellow, or red wavelengths via biomicroscope/contact lens or indirect ophthalmoscope delivery systems, duration of 0.1-0.2 seconds, and spot size of 100-200 micrometers. Apply laser in 3 confluent 360° rings around the lesion. Care should be taken to avoid bare retinal pigment epithelium.

Cryotherapy may be a necessary alternative in cases in which significant hemorrhage prevents laser administration.

Retinal detachment treatments

Frank rhegmatogenous retinal detachment may be treated with a scleral buckling procedure and/or pars plana vitrectomy with gas administration.[17] All areas of lattice and retinal breaks should be meticulously sought after and barricaded with laser or cryotherapy.

Treatment of rhegmatogenous retinal detachment as described under Medical Care.

Retinal detachment may still occur after treatment.

A retinal surgeon may need to be consulted.

Patients with lattice degeneration should undergo annual dilated eye examinations with close attention the peripheral retina.

Educating patients about the symptoms (eg, new-onset floaters, flashes, visual field defects) of a retinal tear or detachment is critical. The necessity of being examined on an emergent basis if symptoms of flashes or floaters occur should be stressed.

Complications are rare with laser retinal treatment, but epiretinal membrane, macular pucker, and/or retinal detachment may occur.[18]

The prognosis is favorable.

Educating patients about the symptoms (eg, new-onset floaters, flashes, visual field defects) of a retinal tear or detachment is critical.