SOLITARY PUNCTATE CHORIORETINITIS

A Unique Subtype of Punctate Inner Choroidopathy

Abstract

Purpose: 

To describe a case series of a special subtype of punctate inner choroidopathy with solitary lesions in the macular area and named solitary punctate chorioretinitis.

Methods: 

This retrospective observational study clinically evaluated 12 eyes from 12 patients diagnosed as punctate inner choroidopathy with solitary lesions. Demographic data and multimodal imaging features were analyzed for the included patients.

Results: 

All the included patients were Chinese and of Han ethnicity. The median age of the included patients was 29.5 years (range: 25–40 years). Most patients (11/12, 91.67%) were myopic, with median refraction errors of −4.4 diopters (D) (range: −8.5 to 0 D). Solitary chorioretinitis lesions were yellow‒white and appeared hyperfluorescent during the entire phase of fundus fluorescein angiography without leakage (9/12, 75%) and hypofluorescent on indocyanine green angiography (11/11, 100%). On spectral domain optical coherence tomography, active inflammatory lesions appeared as isolated, heterogeneous, moderately reflective material at the outer retina (10/12, 83.33%) in the fovea or parafoveal region with disruption of the outer retinal layers. When the inflammatory lesions regressed, the moderately reflective materials in the outer retina were absorbed or regressed with outer retinal tissue loss. Additional sequelae of lesion regression included focal choroidal excavation and intraretinal cystoid space. Secondary choroidal neovascularization was noticed in 2 eyes (2/12, 16.67%).

Conclusion: 

Solitary punctate chorioretinitis is a rare and unique subtype of punctate inner choroidopathy. Solitary punctate chorioretinitis may also be an unrecognized etiology of some forms of focal choroidal excavation and idiopathic choroidal neovascularization.

In Brief

This study reported a unique case series of a subtype of punctate inner choroidopathy, termed “solitary punctate chorioretinitis.” We investigated the clinical and multimodal imaging features of solitary punctate chorioretinitis, and these findings revealed similarities and differences between solitary punctate chorioretinitis and typical punctate inner choroidopathy.

Punctate inner choroidopathy (PIC) is defined as idiopathic posterior uveitis that most commonly occurs in young, myopic women.¹ Currently, PIC is regarded as an entity of “white dot syndrome (WDS),” a heterogeneous group of noninfectious, inflammatory diseases primarily affecting the outer retina and choriocapillaris (CC) and sharing similar epidemiological features.² The prognosis of PIC is usually benign compared with that of other entities of WDS. The severe visual loss among patients with PIC is usually related to the recurrence of PIC and the development of choroidal neovascularization (CNV) in the macular area.^3,4 According to the Standardization of Uveitis Nomenclature Working Group, solitary lesions in WDS are rare. Zero of 144 PIC cases and 0 of 138 multifocal choroiditis and panuveitis cases showed unifocal lesions according to their database.^5–7 Even so, solitary inflammatory lesions in the macular area cannot be neglected in clinical work. Solitary lesions in the macular area can lead to the development of CNV or generate special sequelae, such as focal choroidal excavation (FCE).⁸

We identified a case series of eyes affected with solitary lesions that have the similar characteristics of PIC lesions. However, this subtype of PIC has been poorly reported. In this study, we aimed to differentiate solitary inflammatory lesions from “classic/typical PIC” with multifocal lesions, and we proposed the term “solitary punctate chorioretinitis (SPC)” to describe this subtype of PIC. The findings of our study may expand the varieties of clinical manifestations of PIC and its subtypes. Also, it will deepen the perception of PIC and WDS.

Methods

Subjects

This retrospective observational study was approved by the Institutional Review Board of the Zhongshan Ophthalmic Center. Patients diagnosed with PIC and showing solitary lesions were included for our study between January 2017 and January 2022. This study was conducted at the Zhongshan Ophthalmic Centre and adhered to the tenets of the Declaration of Helsinki. Written informed consent was obtained from all subjects.

The diagnosis of PIC was based on classically accepted clinical findings and a comprehensive ocular and systemic examination.^1,6,9,10 Extensive systemic evaluations, including x-ray, blood work-up, and laboratory inspections, were conducted and excluded infectious and inflammatory systemic diseases, including tuberculosis (chest x-ray, QuantiFERON Gold, and purified protein derivative skin test), syphilis (Venereal Disease Research Laboratory test and rapid plasma reagin test), toxoplasmosis, acquired immune deficiency syndrome (AIDS), sarcoidosis, cat-scratch disease, and histoplasmosis. The definition of “SPC” is based on the findings of multimodal imaging, and only eyes with solitary/unifocal PIC inflammatory lesions were included in this study. Punctate inner choroidopathy inflammatory lesions were differentiated from other lesions according to multimodal imaging findings as follows: Choroidal neovascularization (CNV was identified on optical coherence tomography angiography (OCTA), showing a neovascular network at the outer retinal layer; on fundus fluorescein angiography (FFA), showing well-defined hyperfluorescence at the early phase and dye leakage or staining at the late phase; and on indocyanine green angiography (ICGA), showing a neovascular network with staining. Focal scleral nodule/unifocal helioid chorioretinitis can be differentiated with PIC on enhanced depth imaging-optical coherence tomography (EDI-OCT) that PIC lesion involved the outer retina-retinal pigmented epithelium (RPE)–CC while focal scleral nodule/unifocal helioid chorioretinitis arising from the sclera or outer choroid.^11,12

Imaging Acquisition and Data Analysis

Demographic characteristics and clinical information, including follow-up data and multimodal imaging findings, were collected and analyzed in this study.

Multimodal imaging examinations, including fundus photography (Zeiss FF450 plus fundus camera, Carl Zeiss, Inc., Jena, Germany, or a Topcon 50 VT fundus camera, Topcon Corp, Tokyo, Japan), FFA, ICGA, shortwave fundus autofluorescence (SW-AF), spectral domain optical coherence tomography (SD-OCT) (SPECTRALIS HRA+OCT; Heidelberg Engineering, Heidelberg), and OCTA (AngioVue, RTVue XR Avanti; Optovue, Fremont, CA, V.2015.1.0.90) were performed for included patients at baseline (first visit). One patient did not undergo ICGA examination because of a dye allergy. Multimodal imaging features of the lesions on color fundus photography, SW-AF, OCT, OCTA, FFA, and ICGA were recorded. We also evaluated whether there was staining of the optic disk, retinal vasculitis on FFA, dilation of the choroidal vessels in the early phase of ICGA, and choroidal vascular hyperpermeability manifesting as focal hyperfluorescence in the mid-to-late phase of ICGA. The area of the lesions was measured in the late phase of ICGA (20 minutes after injection) with built-in SPECTRALIS HRA+OCT software. SD-OCT (with EDI) and OCTA were performed during the follow-up period. The subfoveal choroidal thickness was measured from the outer surface of the hyperreflective line ascribed to the RPE to the inner scleral border. The intraretinal cystoid space was identified by OCT as relatively hyporeflective areas in the retina without hyperreflective borders. Focal choroidal excavation was defined as the focal excavation of Bruch membrane into the choroid as determined by SD-OCT without any evidence of posterior staphyloma. Bilateral high-density 6 mm × 6 mm and 3 mm × 3 mm OCTA images were captured for each patient. Automatic segmentation was applied to derive the en face slabs for each vascular plexus, and manual adjustments were performed by researchers (Y.Y.S. and Y.K.Z.) if there was significant error. The outer retinal layers were reviewed for the presence of a neovascular network. Choroidal capillary flow deficit refers to flow changes in the CC layer due to ischemia,¹³ and a hyperintense vascular network within the hypointense area at the level of the CC has been described as a “collection of crippled whitening.”^14,15 The multimodal imaging features of all participants were separately reviewed and assessed by two investigators (Y.H.G. and G.Q.H.). Discrepancies were brought to a fundus specialist (F.W.) for the final determination.

Statistical Analysis

Data were analyzed using SPSS (version 16.0; SPSS, Inc., Chicago, IL). Descriptive statistics are reported as the mean ± SD or number (n) with percentage (%). Patient-related observations were compared using the independent t-test, the paired t-test, the Mann–Whitney U test, the chi-square test, or Fisher exact test, as appropriate. A P value < 0.05 was considered statistically significant.

Results

Patient Demographic and Clinical Data

Twelve eyes of 12 patients were diagnosed with PIC with solitary punctate chorioretinitis (SPC) and included in this study. The included patients were young adults with a median age of 29.5 years (range: 25–40 years). There were six women and six men and no sex predisposition among the included patients. All patients were unilaterally affected, with a median best-corrected visual acuity at baseline of 20/32 (range: 20/400–20/20). Most patients (11/12, 91.67%) were myopic, with a median refraction error of −4.4 diopters (D) (range: −8.5 to 0 D).

All inflammatory lesions appeared as yellow‒white lesions in the subfoveal area, as summarized in Table 1. Therefore, noticeable symptoms were reported by these patients, including blurred vision (n = 9), photopsia (n = 2), and scotoma (n = 2). All included patients had no history of eye disease or trauma. Two patients reported having a cold as a viral prodrome. Systemic evaluation was conducted for all patients, and negative results were found for systemic infection or inflammation. The follow-up duration of patients was at least 6 months (median: 10.5 months, range: 6–48 months). As shown in Table 1, during the follow-up period, all inflammatory lesions regressed spontaneously or after treatments (as shown in Figure 1), but some patients experienced relapse of the inflammation (Figure 2). The median BCVA at last visit was 20/25 (range: 20/62.5-20/20) and there was significant improvement compared to baseline (P = 0.03). The treatments for the included patients varied from regular medical observation without intervention (n = 6) to oral glucocorticoids (n = 4), periocular triamcinolone acetonide injection (n = 2), and intravitreal antivascular endothelial growth factor injection (n = 2). At the latest visit, only some of the eyes (7/12, 58.33%) showed recovery and remained stable. Recurrence of inflammation was found in 3 eyes (3/12, 25.0%). As shown in Figure 3, secondary CNV developed in 2 eyes (2/12, 16.67%). Focal choroidal excavation formed in three eyes during the process of inflammation, while two eyes showed FCE at the initial visit.

Table 1. - Clinical Features of Included Patients

No.	Sex	Age	Affected Eye	BCVA at Baseline	Symptoms	Viral Prodrome	Anterior Chamber or Vitreous Inflammation	Location and Color of Lesion	Treatment	Follow-up Time	BCVA at the Final Visit	Prognosis
1	M	30	OS	20/32	Blurred vision	N	N	SF, yellow‒white	OG	6	20/25	Fully regress
2	F	25	OS	20/200	Blurred vision	N	N	SF, yellow‒white	N	6	20/25	Fully regress
3	M	31	OS	20/100	Blurred vision	N	N	SF, yellow‒white	OG	24	20/32	Formation of FCE
4	M	28	OD	20/40	Blurred vision	N	N	SF, yellow‒white	PITA	48	20/32	Recurrence
5	M	27	OS	20/400	Blurred vision, scotoma	Y	N	SF, yellow‒white	OG, anti-VEGF	24	20/62.5	Recurrence, development of CNV
6	F	33	OD	20/25	Photopsia	N	N	SF, white	OG, PITA	27	20/25	Recurrence
7	M	40	OD	20/32	Scotoma	N	N	SF, yellow‒white	N	12	20/25	Formation of FCE, development of CNV
8	M	37	OS	20/32	Blurred vision	N	N	SF, yellow‒white	N	6	20/20	Formation of FCE
9	F	32	OS	20/25	Blurred vision	Y	N	SF, yellow‒white	N	9	20/20	Fully regress
10	F	28	OS	20/50	Blurred vision	N	N	SF, yellow‒white	Anti-VEGF	12	20/20	Fully regress
11	F	29	OS	20/20	Blurred vision	N	N	SF, yellow‒white	N	6	20/20	Fully regress
12	F	28	OS	20/20	Photopsia	N	N	SF, yellow‒white	N	6	20/20	Fully regress

OG, oral glucocorticoids; PITA, periocular injection triamcinolone acetonide; CNV, choroidal neovascularization; FCE, focal choroidal excavation; VEGF, antivascular endothelial growth factor; M, male; F, female; SF, subfoveal.

Fig. 1.: Multimodal imaging of SPC with full regression (from Patient 2). At the first visit (baseline), (A) fundus photograph showing a yellow‒white lesion in the macular area (green arrow). (B) shortwave fundus autofluorescence showing that the lesion is homogenously hypoautofluorescent (green arrow). (C) at the active inflammatory phase, SD-OCT shows that the lesion involves the outer retina and RPE-BrM-CC and appears as moderately reflective materials over the RPE with discontinuity of the ELM, EZ, and RPE (green arrow). (D) Late-phase FFA showing a small dot lesion that is hyperfluorescent without dye leakage (green arrow). (E) Late-phase ICGA showing a solitary small hypofluorescent dot lesion (green arrow). Two months later, (F) the lesion regressed as the moderately reflective materials disappeared (yellow arrow on OCT with follow-up mode) at the recovery phase.

Fig. 2.: Multimodal imaging of SPC with several episodes of relapse (from Patient 6). A–D. present the multimodal imaging at baseline. At the first visit, (A) a fundus photograph showing a yellow‒white lesion in the macular area (green arrow). (B) En face OCTA of the outer retinal layer showing no signs of neovascularization. (C) En face OCTA of the choriocapillaris layer showing a collection of crippled whitening at the site of the active inflammatory lesion; (D) corresponding SD-OCT showing moderately reflective materials over the RPE with discontinuity of the RPE (green arrow). (E) Fundus photography showing a smaller yellow‒white lesion in the macular area (green arrow). (F) En face OCTA of the outer retinal layer showed no abnormities. (G) The site of SPC left an area of flow deficit on the slab of the choriocapillaris layer of en face OCTA. (H) Corresponding SD-OCT showing the hyporeflective intraretinal cystoid space with disruption of RPE, EZ, and ELM. However, at the 12-month follow-up, the patient complained of photopsia with decreased vision and (I). spectral domain OCT showed the active inflammatory lesion as moderately reflective materials at the previous site. The patient received a periocular injection of triamcinolone acetonide, and the lesion regressed on SD-OCT, as shown in (J and K).

Fig. 3.: Various prognosis of SPC lesions. (A–D). Formation of FCE after the SPC regressed (Patient 3). At the active phase (A) the fundus photograph showing an isolated lesion in the macular area (orange arrow). The green line indicates the corresponding scan of SD-OCT. (B) Spectral domain OCT showing disruption of the RPE with moderately reflective materials over it (orange arrow). When the lesion regressed, at the recovery phase, (C) Spectral domain OCT showing the tissue loss from the photoreceptor layer and inner choroid. Focal choroidal excavation (red arrow) with an intraretinal cystoid space (orange arrow) formed at the site of SPC. (D) En face OCTA image of the choriocapillaris layer at the recovery phase showing the flow deficit area of the macula. (E–K) Development of secondary CNV after SPC regression (Patient 5). At the first visit, (E) the active inflammatory lesion showed a punctate yellow‒white lesion on fundus photography and (F) disruption of the RPE with moderately reflective materials over it on SD-OCT (orange arrow). Six months later, (G) the moderately reflective materials were absorbed with tissue loss at the site of the outer retina on OCT; at the 14-month follow-up, a CNV developed at the site of previous inflammation site. (H) Optical coherence tomography angiography image showing the network of CNV was visualized at the choriocapillaris layer. (I) Corresponding OCT showed hyperreflective CNV (yellow arrow) over the RPE. After one injection of vascular endothelial growth factor (anti-VEGF), (J) the network of CNV decreased on OCTA choriocapillaris layer and (K) the corresponding OCT showed elevation of RPE with remaining subretinal fluid.

Multimodal Imaging Findings

At baseline, there were no signs of hemorrhage or exudation around the lesions in the fundus photograph. Except for the solitary, focal inflammatory lesion at the macula, there were no other abnormal findings. The multimodal imaging characteristics of the lesions in the included eyes are summarized in Table 2. FFA and ICGA were conducted at the first visit when disease onset was suspected. Inflammatory lesions appeared as staining (9/12, 75%) or window defects (3/12, 25%) on FFA. Eleven patients underwent ICGA, and their lesions (11/11, 100%) appeared hypofluorescent on ICGA. The outlines of the lesions were more distinct on ICGA, and the area of the lesions was measured, as summarized in Table 2. The punctate lesions were generally small, with a mean area of 0.83 ± 0.71 µm² (range: 0.12–2.46 µm²). Three eyes (3/11, 27.27%) showed focal choroidal vascular hyperpermeability around the lesions, and one eye (1/11, 9.09%) showed multiple choroidal vascular hyperpermeabilitys at the posterior pole. Fundus autofluorescence examination was performed in all eyes. Most lesions (10/12, 83.33%) showed hypoautofluorescence, and 2 lesions (2/12, 16.67%) showed hypoautofluorescence with a hyperautofluorescent margin.

Table 2. - Multimodal Imaging Features of SPC Lesions

	Active Inflammatory Phase	Recovery Phase	P
SD-OCT features
SFCT, mean ± SD, μm	273.17 ± 69.53	223.75 ± 69.87	0.01*
Outer retinal moderately reflective materials, n (%)	10 (83.33%)	0 (0%)	˂0.001†
RPE disruption, n (%)	11 (91.67%)	6 (50.0%)	0.069‡
Irregularity of RPE, n (%)	11 (91.67%)	3 (25.0%)	0.04†
Hyporeflectivity of intraretinal cystoid space	0 (0%)	6 (50.0%)	0.014‡
FCE	2 (16.67%)	5 (41.67%)	0.371‡
OCTA choriocapillaris segment
Collection of crippled whitening, n (%)	2 (16.67%)	3 (25.0%)	1‡
Flow deficit, n (%)	8 (66.67%)	6 (50%)	0.408†
SW-AF
Hypoautofluorescence, n (%)	10 (83.33%)
HypoAF with hyperAF margin, n (%)	2 (16.67%)
FFA
Appearance of lesions
Staining, n (%)	9 (75.0%)
Window defect, n (%)	3 (25.0%)
Retinal vasculitis, n (%)	0 (0%)
Staining of disk, n (%)	1 (8.33%)
ICGA
Area of lesion, μm2, mean ± SD (range)	0.83 ± 0.71 (0.12–2.46)
CVH
Around lesions, n (%)	3 (27.27%)
Posterior pole, n (%)	1 (9.09%)

Bold entries: P< 0.05.

^*Paired t-test.

^†Chi-square test.

^‡Fisher exact test.

CVH, choroidal vascular hyperpermeability.

SD-OCT and OCTA were conducted for all included patients at every visit, and we recorded the features in the active inflammatory phase and the recovery phase, as summarized in Table 2. Active inflammatory lesions appeared as isolated, heterogeneous, moderately reflective material at the outer retina (10/12, 83.33%) in the macular fovea with disruption of the external limiting membrane (ELM) (10/12, 83.33%), elliptical zone (11/12, 91.67%), and RPE (11/12, 91.67%). When the inflammatory lesions regressed, the moderately reflective materials in the outer retina were absorbed or regressed with outer retinal tissue loss. In most eyes (9/12, 75.0%), continuity of the external limiting membrane was restored, but damage to the RPE (6/12, 50.0%) and elliptical zone layer (6/12, 50.0%) remained. Additional sequelae of lesion regression included FCE and intraretinal cystoid space, as shown in Figure 3. On OCTA, flow deficit in the CC segment was found in 8 eyes (8/12, 66.67%) in the active inflammatory phase, and in 2 eyes, the area of nondetectable flow signal disappeared in the recovery phase. Two eyes (2/12, 16.67%) showed a collection of crippled whitening of the CC in the active inflammatory phase, while three eyes showed this feature in the recovery phase. As mentioned previously, when the lesions regressed, only 58.33% of the eyes remained stable and 2 eyes (2/12, 16.67%) developed secondary CNV with a clear neovascular network on the outer layer of the retina (Figure 3).

Discussion

In this article, we report a unique series of cases presenting with solitary PIC lesions in the macular area and we propose the term SPC to describe this special subtype of PIC. We summarized the clinical characteristics of these lesions, and the median age of the included patients was 29.5 years (range: 25–40 years). Most patients (11/12, 91.67%) were myopic, with a median refraction error of −4.4 D (range: −8.5 to 0 D). These findings showed similar epidemiological prevalence between PIC and its subtype SPC, which usually occurs in young, healthy adults with myopia.¹⁶ The multimodal imaging features of SPC also appeared as typical PIC lesions. Under fundusscopy, these lesions presented as yellow–whitish colored dots. On FFA, lesions usually appeared hyperfluorescent throughout the entire phase (staining on FFA), whereas parts of the lesions showed early hyperfluorescence with late hypofluorescence (window defect) on FFA. On ICGA, all lesions appeared hypofluorescent and the morphology of the lesions was more clearly seen in the late phase of ICGA. We also noticed choroidal vascular hyperpermeability on ICGA, which may have resulted from focal choroidal inflammation and vessel dilation during the active inflammatory phase. On SD-OCT, the lesions appeared as disruptions of the outer retina with moderately reflective materials as active lesions of PIC. On OCTA, flow deficit of the CC segment was observed in most eyes.

On the other hand, SPC, as an extraordinary subtype of PIC, shows distinctive features. The lesions in the foveal area were quite small and ranged from 0.12 µm² to 2.46 µm² in size, allowing them to be easily missed on fundus examination. During a median follow-up of 10.5 months, SPC presented as only a single lesion located in the fovea of the macula and did not increase or appear as multifocal lesions. More interestingly, as shown in Figure 2, some patients underwent relapse of the inflammation. However, inflammation recurred at the same site rather than as more inflammatory lesions at other locations. The reason why SPC develops in the foveal area and recurrent inflammation occurs at the same location is unknown. One of the possible explanations may be the unique anatomy of this region. The foveal avascular zone lacks retinal blood vessels and is mainly supplied by the choroidal circulation. The choroidal arterioles in the macular region have greater volume, higher pressure, and a higher density of choroidal capillaries. Therefore, the macular region is more vulnerable to choroidal inflammation.

The prognosis of SPC also merits attention. These solitary punctate lesions can fully regress, generate intraretinal cystoid space, form FCE, or develop CNV. According to follow-up SD-OCT data, we found that the lesions showed the same recovery process of PIC as we previously reported.^17,18 During the active phase of inflammation, the lesions appeared as disruptions of the outer retina with moderately reflective materials in the outer retina, indicating that the lesions mainly involved the outer retina and choroidal capillaries in the active inflammatory phase. When the inflammatory lesions regressed, the moderately reflective materials at the outer retina were absorbed or regressed and the continuity of the external limiting membrane, elliptical zone, and RPE progressively recovered. The layers of the retina may not fully recover with continuity, and the intraretinal cystoid space can be found during the recovery phase, as shown in Figures 2 and 3. Interestingly, there were no chorioretinal atrophy lesions with pigmentation formed when the inflammatory lesions regressed in these case series. It might be owing to the lesions of SPC were quite small and layers of retina and inner choroid can fully recovery without RPE proliferation. In addition, it may be attributed for the follow-up period is not long enough. During the process of recovery, we noticed that the subfoveal choroidal thickness of the affected eye was significantly decreased. This finding is consistent with a previous study showing that inflammatory cytokines may cause vessel dilation, leading to choroidal thickening at the active inflammatory phase of PIC.^17,19 On the other hand, the significant decrease in subfoveal choroidal thickness may result from the formation of FCE at the fovea. Tissue loss at the outer retina/choroid capillary and RPE/Bruch membrane disruption is suitable for the formation of FCE in chorioretinal inflammation.^20,21 In addition to FCE, the development of CNV at the site of SPC is common, as we reported. Therefore, SPC may be the candidate etiology for idiopathic FCE and idiopathic CNV.

Solitary punctate chorioretinitis should be differentiated from other choroidal granulomas and WDS according to clinical findings and multimodal imaging features. The diagnosis of tuberculoma is based on the Collaborative Ocular Tuberculosis Study diagnostic criteria, indicating that laboratory inspections are essential.²² The diagnosis of sarcoidosis is based on the International Workshop of Ocular Sarcoidosis. Radiological signs such as bilateral hilar lymphadenopathy and the findings of other systemic investigations support the diagnosis.^22,23 In this study, there were no positive findings indicating systemic evidence of tuberculosis or sarcoidosis in our patients. Focal scleral nodules (also known as solitary idiopathic choroiditis/unifocal helioid choroiditis) also manifest as yellow and white solitary choroidal lesions. With the advent of enhanced depth imaging OCT, researchers have revealed that focal scleral nodule may involve the sclera and result in an absent choroidal layer overlying the apex of the lesion and degenerative RPE changes. The application of OCT can be used to distinguish SPC from focal scleral nodule because it mainly involves the outer retina and choroidal capillaries.¹¹ Idiopathic CNV refers to CNV that develops without any predisposing abnormalities. The presence of CNV is demonstrated by dye leakage on FFA and staining on the late phase of ICGA. Moreover, OCTA can also invasively detect CNV. In this study, the multimodal imaging examinations excluded CNV at baseline.

The limitations of this study include its retrospective observational design and small sample size. Solitary punctate chorioretinitis is an unrecognized, rare, and potentially underdiagnosed subtype of PIC. With the findings of our study along with the summarized clinical and multimodal imaging features of SPC, more patients will be correctly diagnosed and recruited in future studies. The follow-up period of our study ranged from 6 to 48 months, and whether these solitary punctate lesions develop into typical multifocal PIC lesions may need longer follow-up observation. Moreover, similar to other forms of WDS, the diagnosis of PIC and its subtype SPC is mainly based on morphological findings. The pathological mechanism of SPC still needs further investigation.

In conclusion, we report a special subtype of PIC and propose that it be referred to as “SPC” with respect to its unique multimodal imaging features and clinical characteristics. Although SPC manifests as tiny, solitary lesions in the macular area and can regress spontaneously, it also requires attention from clinicians. The recurrence of SPC and the development of CNV would cause an apparent decrease in visual acuity because of the anatomical characteristics of SPC. In addition, SPC may also be an unrecognized etiology of some forms of FCE and idiopathic CNV.