A detailed understanding of the anatomy and pathology of the peripheral retina is quintessential for the primary eyecare provider.
There exists a plethora of degenerative retinal conditions that affect structural integrity as well as vascular perfusion that can result in permanent visual impact if left untreated.
In this article, we’ll review some common (and not-so-common) abnormalities and pathologies of the peripheral retina.
Anatomical overview of the retinal periphery
The retinal periphery is classified as the area from the equator to the ora serrata, which is roughly 3 disc diameters.1
Anatomic landmarks that can be used as guidance include:
- Vortex Vein Ampulla: Demarcate the equator of the eye, typically one vortex vein is visualized per quadrant and may appear red or orange in color with a tentacular appearance.1,2
- Long/Short Posterior Ciliary Nerves
- Long Posterior Ciliary Nerves (LPCN): LPCN and arteries are found in the 3 o’clock and 9 o’clock position and run from the ora to the equator. LPCNs are yellow in color and are surrounded by pigment.1,2
- Short Posterior Ciliary Nerves (SPCN): SPCN and arteries are visualized near the vertical meridians and share the same appearance as the LCPNs, yellow with pigmented borders.1,2
- Peripheral Retinal Vessels: Run parallel to the ora serrata.
- Ora Serrata, Pars Plana: The anterior boundary of the neural retina and ciliary body and has a scalloped appearance. Oral bays are extensions of the ciliary body and appear brown with white extensions called dentate processes.
- Dentate processes vary in number (16 to 48 per eye) and may not be present in the temporal retina.
- The pars plana is brown in color and extends from the ora serrata to the ciliary processes.1,2
- Vitreous Base: The connection point of the vitreous and retina, though invisible, it is clinically relevant as it is the anatomic limit of a posterior vitreous detachment.
Figure 1: Retinal anatomic landmarks, such as the vortex veins, LPCN, and SPCN, on widefield color fundus photography (CFP).
Figure 1: Courtesy of Inrava Khasnabish OD, FAAO.
Defining peripheral retinal disease
According to the American Academy of Ophthalmology, peripheral retinal disease is classified by location, pathomorphology, depth of retinal change, risk for retinal detachment, and prognosis.3
In addition, peripheral retinal disease is defined by conditions affecting the outer regions of the retina within the anatomical landmarks that define the peripheral retina (i.e., equator to ora serrata), and is often characterized by degenerative changes, structural abnormalities, or proliferative processes.
Download the Guide to Peripheral Retinal Degenerations
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A Guide to Peripheral Retinal Degenerations
This cheat sheet lists common and rare peripheral retinal diseases with relevant clinical information and fundus photography.
Common peripheral retinal diseases
Lattice degeneration
Lattice degeneration is characterized by sharply demarcated areas of retinal thinning with a lattice-like pattern. It is often associated with high myopia and genetic predisposition.4
Diagnosis involves clinical examination supplemented by imaging modalities like optical coherence tomography (OCT). Treatment may involve prophylactic laser photocoagulation to prevent complications like retinal tears or detachment.4
Figure 2: Lattice degeneration as seen on widefield color fundus photography.
Figure 2: Courtesy of Inrava Khasnabish OD, FAAO.
Cobblestone degeneration
Cobblestone degeneration (also known as pavingstone degeneration) presents as yellow-white patches resembling cobblestones in the peripheral retina. It is commonly observed in aging eyes and high myopia. Diagnosis is made through clinical examination with fundus imaging. Generally, intervention is unnecessary.5
While it is not directly related to geographic atrophy (GA)—found in the advanced form of dry age-related macular degeneration (AMD)—there are pathogenetic similarities in the development of GA and cobblestone degeneration. In cobblestone degeneration, atrophy of the outer retinal layers occurs and provides increased visibility of the underlying choroid, similar to GA.6
Figure 3: Closeup of cobblestone degeneration on fundus photography.
Figure 3: Courtesy of David Almeida, MD, MBA, PhD.
Peripheral reticular degeneration
Peripheral reticular degeneration exhibits a reticular pattern of atrophic changes in the peripheral retina. Risk factors include age-related changes and myopia. Diagnosis is typically through clinical examination and fundus imaging, with no specific treatment required unless complicated by other retinal issues.2
Figure 4: Peripheral reticular degeneration as seen on widefield CFP.
Figure 4: Courtesy of Inrava Khasnabish OD, FAAO.
Peripheral drusen
Peripheral drusen are small yellowish deposits in the peripheral retina, often asymptomatic. Risk factors include age, family history, and factors associated with AMD. Diagnosis involves routine eye exams, particularly with dilated fundus examination or retinal imaging techniques like OCT or fundus photography.7
Management focuses on regular monitoring for progression to advanced AMD and addressing modifiable AMD risk factors like smoking and hyperlipidemia. Treatment options for advanced AMD may be considered if peripheral drusen progresses.
Figure 5: Closeup of peripheral drusen on fundus photography.
Figure 5: Courtesy of David Almeida, MD, MBA, PhD.
For a deep dive into how optometrists can identify retinal disease on OCT imaging, check out Into the Woods: Interpreting OCT Imaging in Retinal Disease!
Peripheral retina biomarkers of AMD
Peripheral reticular degeneration and peripheral drusen both have been associated with patients who have developed AMD. A study done in 2009 investigated the association between six AMD genetic variants and peripheral retinal degenerations, and found links between peripheral drusen and reticular pigment and AMD presence.7
Specifically, the CFH genotypes showed increased risk for peripheral retinal abnormalities, even in individuals with minimal macular disease, thereby suggesting a genetic predisposition beyond central macular involvement.6,7
A pilot study done in 2018 evaluating the correlation between peripheral hard drusen and Alzheimer’s disease found that accumulation of hard drusen in the upper nasal quadrant has the potential to serve as a valuable biomarker for early detection of Alzheimer's disease.8
Vitreoretinal tufts
Vitreoretinal tufts present as small, nodular elevations of the retina and are associated with aging and myopia. Diagnosis is made during retinal examination, often observed as discrete elevations on fundus examination or imaging modalities like OCT.9
Typically benign and asymptomatic, vitreoretinal tufts require no specific treatment unless complicated by other retinal issues like holes, tears, or detachments.9 Annual monitoring is recommended.
Figure 6: Closeup of vitreoretinal tufts on fundus imaging.
Figure 6: Courtesy David Almeida, MD, MBA, PhD.
Retinal holes
Retinal holes are full-thickness defects in the retinal tissue that can lead to retinal detachment if untreated. Risk factors include myopia, trauma, lattice degeneration, and age-related changes.
Diagnosis is made through retinal examination, visible as round or oval lesions with smooth margins. Management options include prophylactic laser treatment to prevent retinal detachment in high-risk cases and surgical intervention if detachment occurs.9
Figure 7: Retinal hole on widefield CFP.
Figure 7: Courtesy of Inrava Khasnabish OD, FAAO.
Check out the Guide to Peripheral Retinal Diseases!
Retinal tear
Retinal tears involve a disruption of the retinal tissue and are associated with symptoms like floaters, flashes of light, or a curtain-like shadow in the vision. Risk factors are similar to retinal holes.
Diagnosis involves retinal examination, typically visible as linear or horseshoe-shaped breaks in the retina. Treatment includes prompt laser photocoagulation or cryotherapy to prevent progression to retinal detachment, with surgical intervention necessary for complex tears or detachments.10
Figure 8: A retinal tear that is in post-repair status and demonstrates laser photocoagulation scarring on widefield CFP.
Figure 8: Courtesy of Inrava Khasnabish OD, FAAO.
Figure 9: A giant retinal tear on widefield CFP.
Figure 9: Courtesy of Inrava Khasnabish OD, FAAO.
Retinoschisis
Retinoschisis is characterized by the splitting of the retinal layers, often occurring in the outer plexiform layer or inner nuclear layer.5 Risk factors include myopia, age-related changes, and hereditary factors.
Diagnosis is made through retinal examination, typically visible as bullous or cystic elevations of the retina. Observation may be sufficient for asymptomatic cases, with surgical intervention considered for symptomatic or progressive cases, particularly if complications like retinal detachment develop.2,9
Figure 10: Retinoschisis on widefield CFP.
Figure 10: Courtesy of Inrava Khasnabish OD, FAAO.
Figure 11: Another image of retinoschisis on widefield CFP.
Figure 11: Courtesy of Inrava Khasnabish OD, FAAO.
Peripheral microcystoid degeneration
Peripheral microcystoid degeneration is characterized by small cyst-like spaces within the retina, typically located in the peripheral retina.2 Patients are often asymptomatic, and this may be incidentally detected during routine eye examinations.
Risk factors for peripheral microcystoid degeneration include aging and myopia. Diagnosis is made through clinical examination and fundus imaging, where the characteristic cyst-like spaces may be observed.
Treatment is usually not required as the condition is generally benign and asymptomatic, with management focusing on regular monitoring for any changes or progression. If complications such as retinal detachment occur, appropriate intervention may be necessary.9
Figure 12: Closeup of peripheral microcystoid degeneration on fundus imaging.
Figure 12: Courtesy David Almeida, MD, MBA, PhD.
Retinal tumors
Retinal tumors are benign or malignant growths involving the retina, often detected during routine eye examination or if associated symptoms occur. Risk factors vary depending on the type of tumor but may include genetic predisposition, UV exposure, or immunosuppression.
Examples of retinal tumors can include:
- Retinoblastoma
- Melanoma
- Retinal hemangioma
- Retinal capillary hemangioma
- Cavernous hemangioma
- Retinal vasoproliferative tumor
- Racemose hemangiomatosis
- Choroidal hemangioma
- Diffuse choroidal hemangioma
Diagnosis involves retinal examination, imaging studies, and possibly biopsy for definitive diagnosis. Treatment varies depending on the type and extent of the tumor and may include observation, laser therapy, cryotherapy, radiation therapy, or surgical removal.11,12
Figure 13: Central retinoblastoma on fundus imaging.
Figure 13: Courtesy of Inrava Khasnabish OD, FAAO.
The connection between the peripheral retina and systemic disease
Blood supply to the peripheral retina originates from the choroid, which is supplied by the posterior ciliary arteries. The posterior ciliary arteries are branches of the ophthalmic artery that branch off the internal carotid artery.
Vascular anomalies can occur at any point along this pathway, which illustrates the direct impact peripheral retinal degenerations or anomalies may have when it comes to carotid artery disease and ischemic processes. More specifically, cobblestone degeneration and peripheral retinal drusen are most closely related to atrophy of the outer retinal layers.
Early changes in the outer retinal layers can be indicative of systemic anomalies early on in the disease process.6,8
Co-management of peripheral retinal diseases
Peripheral retinal changes are oftentimes asymptomatic and incidental, and for this reason, long-term management is variable. In higher-risk patients, a strong referral network offers the patient and clinician peace of mind.
Working closely with retina specialists in addition to primary care providers is essential in providing optimal patient care and maximizing visual outcomes.
In the asymptomatic patient, close monitoring with dilation and ancillary testing (e.g., OCT, widefield fundus photography, B-scan ultrasound) can provide additional insight into potential problem areas in the retina.
In conclusion
As optometrists, it is imperative we have a thorough understanding of the peripheral retina. It is crucial to be able to differentiate between relatively benign findings and true retinal pathology, as some retinal diseases have sight or potentially life-threatening implications.
Prompt diagnosis and management of degenerative retinal conditions is critical to prevent permanent vision loss. A critical understanding of the vasculature of the peripheral retina also emphasizes the critical role ocular anomalies play in systemic conditions, including carotid artery disease, Alzheimer’s disease, and other ischemic anomalies.
In addition, establishing a good referral network with primary care physicians and retina specialists allows eyecare providers to optimize the visual outcome of their patients and manage their systemic health to the highest allowable standard.
