Role of fundus autofluorescence imaging in the management of submacular hemorrhage

Abstract

Purpose

To evaluate the baseline characteristics of fundus autofluorescence (FAF) in patients with submacular hemorrhage (SMH).

Methods

This retrospective study included patients diagnosed with treatment-naive, foveal-involving subretinal hemorrhage (size > 2-disc diameters) of any etiology, presenting between June 2017 and June 2023. Only cases with good-quality color fundus photographs, optical coherence tomography (OCT) scans, and blue-light FAF images at baseline were included. SMH imaging characteristics were documented and correlated with treatment outcomes. A successful treatment outcome was defined as the reduction, displacement or clearance of the SMH from beneath the fovea.

Results

Nineteen cases of SMH (13 males, 6 females), ranging from 14 to 85 years, were analyzed. Neovascular age-related macular degeneration (nAMD) was the most common etiology (n = 11, 58%). Baseline visual acuity ranged from 6/9 to counting fingers at ½ meter, with a median presentation time of 7 days from symptom onset (range: 1–57 days). Treatment success was observed in 13 eyes (68%). Hypoautofluoroscence on FAF was significantly associated with SMH resolution (p = 0.021). However, no association was found between treatment success and clinical hemorrhage characteristics (p = 0.222), OCT findings (p = 0.222), or specific treatments (p > 0.05). Hypoautofluoroscence on FAF was the sole predictor of treatment success, as demonstrated by Spearman’s correlation (r = 0.637; p = 0.003) and linear regression analysis (p = 0.003).

Conclusion

FAF, in conjunction with color fundus photography and OCT, may provide valuable insights for clinicians in formulating treatment strategies for patients with SMH. Hypoautofluoroscence on FAF was a significant predictor of successful SMH resolution in this study.

Introduction

Submacular hemorrhage (SMH) refers to the accumulation of blood resulting from choroidal or retinal circulation between the neurosensory retina and retinal pigment epithelium, at the posterior pole within the macular region [1]. Significant accumulation of SMH can be caused by a number of conditions, but is most commonly linked to neovascular age-related macular degeneration, trauma, high myopia, retinal arterial macroaneurysm, and presumed ocular histoplasmosis [2–6]. The immediate action which needs to be considered in the management of SMH is the early evacuation of blood from below the fovea as the released toxins from the blood, diffusion barrier created by the blood for oxygen delivery and nutrition to the outer retinal layers and outer retinal shear forces damage the photoreceptors and contribute to permanent visual deterioration [7]. Damage to photoreceptors in the fovea can occur as early as 24 h after the onset of SMH [8].

Currently, there is no “gold standard” treatment for acute SMH management. In order to remove blood from underneath the fovea, a variety of surgical and non-surgical procedures are typically considered. A clinician’s decision regarding the management of SMH is influenced by a number of factors, including the presenting visual acuity, the etiology of the SMH, the duration of visual symptoms, the color, location, extent, and density of the heme, the availability of intraocular gases and tissue plasminogen activator (tpA), and the availability of facilities for pars plana vitrectomy [9]. When planning management of SMH, the duration of visual symptoms and heme characteristics clinically are the most frequently considered factors. The duration of visual symptoms reported by the patient can at times be unreliable. In addition, heme characteristics obtained from a clinical examination or fundus photographs may mislead the clinician regarding the optimal treatment option for the patient. Several recent case series have examined the efficacy of combination therapy involving intravitreal gas injection, intravitreal tissue plasminogen activator (tpA), and/or intravitreal anti-vascular endothelial growth factor (VEGF) injection for the treatment of SMH [10–15]. The duration of symptoms observed in these case series was found to be less than 15 days. In one study, it was asserted that patients who sought treatment promptly after the onset of symptoms experienced successful outcomes [14]. Conversely, Karamitsos et al. conducted a separate study which demonstrated effective management of SMH through the administration of intravitreal gas and tpA injection, irrespective of the size and duration of the hemorrhage [15].

In routine clinical practice, retinal imaging of the macula with optical coherence tomography (OCT) is regularly employed to assess the density and thickness of SMH at the fovea and the presence of underlying etiology [16]. Fundus autofluorescence (FAF), an easily accessible and non-invasive imaging modality, could provide useful information regarding the precise extent of the hemorrhage, the status of the blood in the subretinal space, and the presence of any other associated macular pathology. Heme located anterior to the retinal pigment epithelium exhibit initial hypoautofluoroscence as a result of absorption of the excitation light and obstruction of underlying retinal pigment epithelium [17]. However, these hemorrhages may subsequently transition to a state of hyperautofluorescence following the process of organization. This property of the FAF in SMH needs to be explored further for its effective management. In cases of SMH, enface imaging with short blue wavelength FAF is rarely utilized. Fukuda et al. studied the utility of Optos ultra-widefield green wavelength (FAF) imaging for postoperative follow-up of gas-filled eyes after vitrectomy with subretinal tissue-plasminogen activator (tpA) injection for subretinal hemorrhage displacement and found it to be extremely useful [18].

With this background, we retrospectively studied the baseline characteristics of FAF and correlated it with the retinal OCT and color fundus imaging findings in cases of SMH due to any etiology. This study’s findings could serve as a guide for use of FAF in the management of SMH.

Methods

We conducted a retrospective study at a tertiary eye care center in South India to evaluate the baseline characteristics of SMH and their correlation with treatment outcomes. Data were collected from patients who presented to the retina department between June 2017 and June 2023 with a diagnosis of treatment-naive, foveal-involving subretinal hemorrhage (size > 2-disc diameters) of any etiology. Only cases with good-quality color fundus photographs (CFP), OCT, and blue-wavelength FAF images were included. Patients were excluded if the SMH did not involve the fovea, was ≤ 2-disc diameters in size, or if media opacities impaired image quality. Additionally, patients with pre-existing retinal conditions such as retinal tears, diabetic retinopathy, retinal vein occlusion, or intravitreal hemorrhage, and those with a history of previous photodynamic or laser therapy, were excluded.

Patient demographics, including age, gender, and affected eye, were recorded. Detailed history of the subretinal bleed, including probable etiology, presenting symptoms, time from symptom onset to clinic presentation, best-corrected visual acuity (BCVA), clinical findings from CFP, OCT, and FAF, treatment received, and follow-up details were also documented.

At baseline, all patients underwent imaging with CFP, OCT, and FAF, and the findings were independently evaluated in a masked fashion by three separate readers: CFP by AC, OCT by RM, and FAF by RK. CFPs were obtained using either the Topcon TRC-Dx 50 (Topcon Healthcare, NJ, USA) or the ultra-wide-field Optos^® Daytona (Optos, UK) fundus camera. The color of the SMH (red or yellow) was noted, along with other relevant findings, such as choroidal neovascular membranes, subfoveal disciform scars, choroidal ruptures, and optic disc pallor. OCT images were assessed for the reflectivity and back shadowing of the subretinal hemorrhage, as well as the presence of choroidal neovascularization or rupture at the fovea. FAF images were evaluated to determine whether the subretinal hemorrhage displayed hypo- or hyper-autofluorescence across the lesion.

Treatment aimed primarily at displacing or eliminating the SMH from beneath the fovea while addressing the underlying cause. Treatment options included observation, intravitreal gas injection, intravitreal tissue plasminogen activator (tPA), intravitreal anti-VEGF injection, focal laser, and pars plana vitrectomy, used individually or in combination. The treatment plan was determined at the clinician’s discretion. Treatment success was defined as the reduction, displacement or elimination of hemorrhage from beneath the fovea, evaluated during follow-up visits within 3 months after presentation as observed on CFP and confirmed by OCT and FAF imaging.

All patients provided written informed consent, and the study was approved by the Institutional Review Board in adherence to the Declaration of Helsinki.

Statistical analysis

Statistical analysis for this study was conducted using GraphPad Prism version 10.0.3 (275) for Windows (GraphPad Software, San Diego, California, USA, www.graphpad.com). Continuous variables were presented as mean ± standard deviation, while categorical variables were expressed as numbers and percentages. Non-parametric statistical tests were employed throughout the analysis. Fisher’s exact test was used to compare categorical data from retinal imaging features and treatment modalities with the successful displacement of SMH. Correlations between findings from different retinal imaging modalities and treatment outcomes were evaluated using Spearman’s correlation test. For correlation analysis, binary retinal imaging features were numerically coded as follows: CFP: red = 1, yellow = 0; OCT: heterogeneous hyper- and hyporeflectivity = 1, homogeneous hyperreflectivity = 0; FAF: hypo = 1, hyper = 0. Linear regression analysis was performed, with treatment outcome as the dependent variable, to assess the relationship between OCT, FAF, and CFP features. A p-value of < 0.05 was considered statistically significant.

Results

We identified 80 patients with a diagnosis of subretinal hemorrhage of any etiology from June 2017 to June 2023 using our electronic medical record system. The fovea was involved in 42 (53%) of the 80 patients who had subretinal hemorrhage > 2DD in size. At the baseline visit, 19 (45%) of the 42 patients had access to high-quality CFP, as well as FAF and OCT scans. As a result, 19 eyes from 19 patients were included in the study analysis. The remaining patients were excluded from the study due to the subretinal haemorrhage’s non-involvement of the fovea or a lack of high-quality retinal imaging and OCT scans. There were 13 (68%) males and 6 (32%) females in this case series. The mean age of the study participants was 47.63 ± 22.18 years (range:14–85 years). In 13 (68%) and 6 (32%) eyes, respectively, the right and left eyes were involved. The most common etiology for SMH was neovascular age related macular degeneration (n = 11, 58%). Following this were blunt trauma (n = 7, 37%) and CNVM due to pathological myopia (n = 1, 5%). At the time of presentation, all of the patients complained of visual symptoms. At the baseline visit, the visual acuity in these study eyes ranged from 6/9 to counting fingers at ½ mt. The median time interval between the patient’s perception of visual symptoms and presentation to the retina clinic was 7 days (range: 1–57 days). On the CFP, the blood was red in 16 (84%) eyes, while it was yellow in the remaining 3 (16%). On OCT, the subretinal blood displayed heterogeneous hyper and hyporeflectivity with back shadowing in 16 (84%) eyes and hyperreflectivity with back shadowing in 3 (16%) eyes respectively. On FAF, 16 (84%) eyes had hypoautofluoroscence, while 3 (16%) had hyperautofluorescence at the macula. In 10 (53%) eyes, pneumatic displacement (PD) with intravitreal gas injection was attempted with equal number of eyes treated with and without (n = 5, 26%) intravitreal tpA injection. Other treatment options considered included intravitreal antiVEGF injections in 8 (42%) eyes and pars plana vitrectomy in 2 (10%) eyes. In 4 (21%) eyes, no treatment was provided (Table 1).

Table 1.

Individual case details at presentation

Case No.	Age	Sex	Eye	Presenting visual acuity	Etiology	Time interval between symptoms and presentation in days	Heme colour	Optical coherence tomography	Fundus autofluorescence	Treatment taken	Treatment outcome	Final visual acuity	Total follow-up duration in days
1	54	M	RE	FC at 20 cm	nAMD	7	Red	Heterogenous hyper and hyporeflectivity	Hypo	PD + IV TpA	Success	6/48	3
2	14	M	LE	HM	Trauma	2	Red	Heterogenous hyper and hyporeflectivity	Hypo	Observation	Failure	6/48	19
3	71	M	RE	FCCF	nAMD	20	Red	Heterogenous hyper and hyporeflectivity	Hyper	PPV	Failure	FC at ½ mt	133
4	38	F	RE	6/36	Trauma	4	Red	Heterogenous hyper and hyporeflectivity	Hypo	PD + IV TpA	Success	6/12	56
5	53	M	LE	FC at 1 ½ mt	nAMD	20	Yellow	Homogenous hyperreflectivity	Hyper	PPV + SR TpA	Failure	FC at 1 ½ mt	49
6	85	M	LE	6/9	nAMD	5	Red	Heterogenous hyper and hyporeflectivity	Hypo	IV AntiVEGF	Success	6/9	66
7	42	F	LE	6/24	nAMD	4	Red	Heterogenous hyper and hyporeflectivity	Hypo	PD + IV AntiVEGF	Success	6/8	985
8	22	M	RE	6/96	Trauma	2	Red	Heterogenous hyper and hyporeflectivity	Hypo	PD	Success	6/36	34
9	72	F	RE	6/24	nAMD	7	Red	Heterogenous hyper and hyporeflectivity	Hypo	Observation	Success	6/12	57
10	30	M	RE	6/120	Trauma	1	Red	Heterogenous hyper and hyporeflectivity	Hypo	Observation	Failure	6/120	350
11	73	M	RE	6/18	nAMD	10	Red	Heterogenous hyper and hyporeflectivity	Hypo	PD + IV TpA + IV AntiVEGF	Success	6/18	44
12	14	M	RE	6/36	Trauma	18	Red	Heterogenous hyper and hyporeflectivity	Hypo	PD	Success	6/9	65
13	65	F	LE	6/120	nAMD	57	Yellow	Homogenous hyperreflectivity	Hypo	PD + IV TpA + IV AntiVEGF	Success	6/48	11
14	74	F	RE	FC at ½ mt	nAMD	14	Red	Heterogenous hyper and hyporeflectivity	Hypo	PD + IV TpA + IV AntiVEGF	Success	FC at ½ mt	30
15	20	M	LE	FC at 1 ½ mt	Trauma	2	Red	Heterogenous hyper and hyporeflectivity	Hypo	PD	Success	6/24	21
16	27	M	RE	6/9	Myopia	4	Red	Heterogenous hyper and hyporeflectivity	Hypo	IV AntiVEGF	Success	6/9	1478
17	54	M	RE	1/60	Trauma	1	Red	Heterogenous hyper and hyporeflectivity	Hypo	Observation	Failure	6/30	3
18	53	M	RE	6/15	nAMD	9	Yellow	Homogenous hyperreflectivity	Hyper	PD + IV AntiVEGF	Failure	6/15	7
19	53	F	RE	6/60	nAMD	7	Red	Heterogenous hyper and hyporeflectivity	Hypo	IV AntiVEGF	Success	6/30	30

Abbreviations M – male; F – female; RE – right eye; LE – left eye; FC – finger counting; nAMD – neovascular age related macular degeneration; PD – pneumatic displacement; IV TpA – intravitreal tissue plasminogen activator; PPV – pars plana vitrectomy; SR TpA – sub retinal tissue plasminogen activator; IV AntiVEGF – intravitreal anti vascular endothelial growth factor

Blood was successfully displaced or resolved from below the fovea in 13 (68%) eyes. In 11 (58%) eyes, the visual acuity improved by > 2 Snellen lines and ranged from 6/9 to counting fingers at ½ mt at the last follow-up visit. The total duration of the follow-up ranged from 3 to 1478 days. The Tables 2 and 3; Figs. 1, 2, 3, 4 and 5 provide an analysis of the relationship between the characteristics of the SMH as determined by retinal imaging and the patient’s treatment and the final outcome of the SMH. On using the Fisher’s exact test, there was a statistically significant relationship between heme characteristics on the FAF and heme shifting away from the fovea. Eyes exhibiting hyper autofluorescence on FAF demonstrated SMH resolution failure (p = 0.021). In contrast, neither clinical heme characteristics (p = 0.222) nor OCT scans (p = 0.222) of the retina were associated with the success or failure of SMH resolution (Table 2). Even the treatment modality used in the management of SMH did not show statistically significant relationship with the outcome of SMH resolution (Table 3). Spearman’s correlation matrix showed a positively significant correlation of hypo FAF finding with successful treatment outcome (r = 0.637; p = 0.003) [Table 4]. In terms of linear regression analysis, it was observed that FAF emerged as the only retinal imaging modality that demonstrated potential utility in predicting the effective management of SMH (Table 5).

Table 2.

Relation of SMH characteristics with treatment outcome

Characteristics of SMH		Outcome of SMH		P value
		Success	Failure
Colour of heme on CFP	Red (n = 16)	12 (75)	4 (25)	0.222
	Yellow (n = 3)	1 (33)	2 (67)
Reflectivity of heme on OCT	Heterogenous hyper and hyporeflectivity (n = 16)	12 (75)	4 (25)	0.222
	Hyperreflectivity (n = 3)	1 (33)	2 (67)
Autofluorescence of heme on FAF	Hypoautofluoroscence (n = 16)	13 (81)	3 (19)	0.021
	Hyperautofluorescence (n = 3)	0 (0)	3 (100)

Abbreviations CFP – colour fundus photograph; OCT – optical coherence tomography; FAF – fundus autofluorescence; SMH – sub macular hemorrhage

Table 3.

Relation of treatment taken with treatment outcome

Treatment	Outcome of SMH		P value
	Success	Failure
PD with intravitreal TpA (n = 5)	5 (100)	0 (0)	0.128
PD without intravitreal TpA (n = 5)	4 (80)	1 (20)	> 0.999
Observation (n = 4)	1 (25)	3 (75)	0.071
Intravitreal AntiVEGF (n = 8)	7 (88)	1 (12)	0.177
PPV (n = 2)	0 (0)	2 (100)	0.088

Abbreviations SMH – sub macular hemorrhage; PD – pneumatic displacement; TpA – tissue plasminogen activator; VEGF – vascular endothelial growth factor; PPV – pars plana vitrectomy

Fig. 1.

Clinical and imaging findings of case 4. A 38-year-old-female with history of blunt trauma following fist injury presented to the retina clinic after 4 days from the onset of trauma. Her presenting visual acuity was 6/36. A-E On clinical examination, submacular hemorrhage (SMH) was noted with preexisting choroidal rupture adjacent to the fovea. Colour of the SMH was red. Fundus autofluorescence image showed hypoautofluoroscence due to the heme. Optical coherence tomography (OCT) scan showed SMH and choroidal rupture. heterogenous hypo and hyperreflectivity was noted due to the SMH on OCT. She was treated with intravitreal gas injection (0.5 cc 100% Sf6 gas) and 25mcg of intravitreal tissue plasminogen activator injection. At the final follow-up 56 days after treatment, there was complete resolution of SMH from the fovea and visual acuity improved to 6/12

Fig. 2.

Clinical and imaging findings of case 1. A 54-year-old-male presented to the retina clinic after 7 days following the onset of sudden decrease in vision. His presenting visual acuity was counting fingers at 20 cm. A-E: On clinical examination, submacular hemorrhage (SMH) was noted secondary to neovascular age related macular degeneration. Colour of the SMH was red. Fundus autofluorescence image showed hypoautofluoroscence due to the heme. Optical coherence tomography (OCT) scan showed SMH with heterogenous hypo and hyperreflectivity. He was treated with intravitreal gas injection (0.5 cc 100% Sf6 gas) and 25mcg of intravitreal tissue plasminogen activator injection. At the final follow-up 3 days after treatment, there was reduction of SMH from the fovea and visual acuity improved to 6/48

Fig. 3.

Clinical and imaging findings of case 13. A 65-year-old-female presented to the retina clinic after 57 days following her visual symptoms. Her presenting visual acuity was 6/120. A-E: On clinical examination, submacular hemorrhage (SMH) was noted secondary to neovascular age related macular degeneration. Colour of the SMH was yellow. Fundus autofluorescence image showed hypoautofluoroscence due to the heme. Optical coherence tomography (OCT) scan showed subretinal hemorrhage with homogenous hyperreflectivity due to the heme. She was treated with intravitreal gas injection (0.5 cc 100% Sf6 gas), 25mcg of intravitreal tissue plasminogen activator injection and intravitreal anti vascular endothelial growth factor (Inj. Brolucizumab 6 mg/0.05 ml) injection simultaneously. At the final follow-up 11 days after treatment, there was significant resolution of SMH from the fovea with presence of subfoveal choroidal neovascular membrane and visual acuity improved to 6/48

Fig. 4.

Clinical and imaging findings of case 5. A 53-year-old-male presented to the retina clinic after 20 days following his visual symptoms. His presenting visual acuity was counting fingers at 1 ½ meters. A-E: On clinical examination, submacular hemorrhage (SMH) was noted secondary to neovascular age related macular degeneration. Colour of the SMH was yellow. Fundus autofluorescence image showed hyperautofluorescence due to the heme. Optical coherence tomography (OCT) scan showed subretinal hemorrhage with homogenous hyperreflectivity due to the heme. He was treated with pars plana vitrectomy with simultaneous use of 50mcg subretinal tissue plasminogen activator. At the final follow-up 49 days after treatment, there was still persistence of SMH at the fovea with no improvement in visual acuity

Fig. 5.

Clinical and imaging findings of case 3. A 71-year-old female presented to the retina clinic 20 days after the onset of visual symptoms. Her presenting visual acuity was counting fingers close to the face (CFCF). A-I: Clinical examination revealed a massive submacular hemorrhage (SMH) larger than 2-disc diameters, secondary to neovascular age-related macular degeneration. The SMH, which involved the fovea, appeared predominantly yellow in color with patches of fresh red blood away from the macula on the superior aspect of the optic disc. FAF imaging showed that a significant portion of the hemorrhage exhibited hyperautofluorescence, while OCT revealed heterogeneous reflectivity with both hyper- and hyporeflective areas. She was treated with pars plana vitrectomy, combined with a subretinal injection of 50 mcg tissue plasminogen activator and gas endotamponade. At 2- and 4-week follow-ups, her visual acuity remained unchanged, and the hemorrhage at the macula and fovea showed no signs of resolution, leading to a classification of treatment failure. By the last follow-up, 4½ months after surgery, the SMH had resolved, but extensive damage to the photoreceptors and retinal pigment epithelium was noted. Her final visual acuity was counting fingers at ½ meter

Table 4.

Correlation between the different retinal imaging features and treatment outcome using the Spearman’s correlation test

Treatment outcome vs.	Colour fundus photograph	Optical coherence tomography	Fundus autofluorescence
r value	0.3269	0.3269	0.6374
95% confidence interval	-0.1496 to 0.6801	-0.1496 to 0.6801	0.2578 to 0.8465
R squared	0.1068	0.1068	0.4063
P value	0.172	0.172	0.003

Table 5.

Linear regression analysis between retinal imaging features and treatment success in patients with sub macular hemorrhage

		Colour fundus photograph	Optical coherence tomography	Fundus autofluorescence
Best-fit values	Slope	0.2564	0.2564	0.5
	Y-intercept	0.6667	0.6667	0.5
	X-intercept	-2.6	-2.6	-1
	1/slope	3.9	3.9	2
Std. Error	Slope	0.1798	0.1798	0.1466
	Y-intercept	0.1487	0.1487	0.1213
95% Confidence Intervals	Slope	-0.1230 to 0.6358	-0.1230 to 0.6358	0.1907 to 0.8093
	Y-intercept	0.3529 to 0.9805	0.3529 to 0.9805	0.2441 to 0.7559
	X-intercept	-infinity to -0.5914	-infinity to -0.5914	-3.771 to -0.3171
Goodness of Fit	R squared	0.1068	0.1068	0.4063
	Sy.x	0.3643	0.3643	0.297
P value		0.172	0.172	0.003

Discussion

This study elucidated the significance of FAF in conjunction with other retinal imaging techniques, namely OCT and CFP, in eyes with SMH. The study aimed to determine the significance of FAF in eyes with SMH in order to anticipate the outcome of SMH displacement from beneath the fovea after intervention. The study observed that the occurrence of hyperautofluorescence of SMH on FAF during initial examination was linked to unfavourable outcomes. Conversely, the presence of hypoautofluoroscence of the SMH on FAF was associated with successful displacement of the heme, regardless of the treatment employed.

In order to comprehensively understand the retinal imaging findings discussed in the study, it is imperative to possess a fundamental understanding of the alterations occurring in the extravasated subretinal blood. The extravascular subretinal space experiences leakage or extravasation of blood as a result of an acute injury to retinal or choroidal circulation, regardless of the underlying cause. Subsequently, two events are triggered. The first event involves the activation of the coagulation cascade through platelet activation and aggregation, leading to the formation of a fibrin meshwork within the blood vessels to impede continuing hemorrhage. The second event pertains to alterations in the blood within the subretinal space [19]. The fresh subretinal blood contains a mixture of plasma, red blood cells, white blood cells, and platelets [20]. The composition of this blood undergoes alterations over time. With time, the red blood cells located in the subretinal space experience ongoing disintegration, referred to as haemolysis. Upon the completion of the haemolysis process, the initially red-coloured fresh blood undergoes a transformation, resulting in a change to a yellow hue within the subretinal space [21]. Concurrently, there is a persistent buildup of fibrin [21, 22]. Therefore, the concentration of fibrin in a recently formed subretinal blood clot is either absent or minimal, whereas in an older blood clot, it is significantly elevated. The absence of fibrin and minimal hemolysis contribute to the characteristic red appearance and increased mobility of a recent subretinal hemorrhage. This type of hemorrhage exhibits heterogeneous hypo and hyperreflectivity with back shadowing on OCT and hypoautofluoroscence on FAF. In contrast, an older altered blood presents as yellow, with reduced mobility. It displays homogeneous hyperreflectivity within the subretinal space on OCT and hyperautofluorescence on FAF. These differences can be attributed to the accumulation of fibrin and complete haemolysis in the older hemorrhage. The observed hypoautofluoroscence and hyperautofluorescence patterns observed on FAF in eyes with recent and longstanding SMH can be attributed to the inherent properties of the fluorescence excitation and emission spectra of whole human blood, fibrinogen, and fibrin. The fluorescence spectrum of whole human blood spans a wavelength range of 850 to 1,500 nm, with an excitation wavelength of 808 nm [23]. On the other hand, fibrinogen and fibrin exhibit a fluorescence emission spectrum within the wavelength range of 300 to 400 nm, with the emission peak occurring at 344 nm [24, 25]. Therefore, it can be inferred that short wavelength FAF imaging is a viable method for comprehending the heme properties by evaluating the levels of whole blood and fibrin present. This information could potentially assist the clinician in making an informed decision regarding the selection of the most suitable treatment modality for the displacement of blood located beneath the fovea within the subretinal space.

SMH is associated with poor visual prognosis due to several different mechanisms including direct toxicity from the haemorrhage, mechanical traction on the photoreceptors and the establishment of a barrier effect between the photoreceptors and retinal pigment epithelium [7]. The primary objective in the treatment of SMH is to displace the blood from underneath the fovea so as to protect the photoreceptors from any damage. The rapid clearing of the SMH from underneath the fovea can be achieved by using vitrectomizing techniques with pars plana vitrectomy and non-vitrectomizing procedures such PD with intravitreal gas injection combined with or without the use of tpA [26–30]. For achieving success with PD, the SMH needs to be fresh, mobile and without extensive fibrin. The role of tpA in the management of SMH is to prevent the development of fibrin by activating the plasminogen to plasmin which is a fibrinolytic agent [31, 32]. By inhibiting the fibrin development by the use of tpA, the blood in the subretinal space is kept mobile, there by achieving higher success with PD. Once a dense fibrin is formed in a chronic SMH, the tpA has a very limited success in disintegrating the formed fibrin. Thus, the chances of failure with PD are higher in such situations. The presence of hyperautofluorescence in the area of SMH could act as a guide to determine the degree of fibrin present within the SMH. Thus, the FAF signals in the area of SMH could serve as a surrogate marker for the use of PD along with the use of tpA in the management of SMH and also could serve as a guide for predicting final outcome.

In contrast, the OCT offers valuable insights into the specific localization of blood within the eye [16]. However, it offers only limited details regarding blood properties, such as mobility, the existence of haemolytic red blood cells, and the extent of fibrin content. Also, a very thin film of blood missed on OCT, can be identified on FAF. Consequently, the utilization of OCT as a standalone method may prove to be ineffective in formulating suitable strategies for the management of SMH. While the CFP may offer insights into the extent of hemorrhage, it does not offer comprehensive data on the haemolytic alterations and fibrin composition of the blood. Therefore, the use of the FAF appears to be a valuable imaging modality in comparison to CFP.

This study has several limitations. The small sample size was the primary limitation, mainly due to the stringent inclusion criteria. The objective was not only to describe the characteristics of SMH on FAF in conjunction with OCT and CFP, but also to demonstrate the utility of these imaging modalities in guiding appropriate management. Additionally, the study did not compare treatment outcomes across different treatment modalities. A larger sample size would have been necessary to draw meaningful conclusions about the effectiveness of various treatment options. Another limitation was the use of blue-light FAF, which may have affected the FAF patterns due to its interaction with macular pigments. Using green-light FAF could have provided better insight into the characteristics of the subretinal hemorrhage.

Despite these limitations, the study has several notable strengths. The findings have the potential to improve our understanding of the changes occurring in extravascular blood within the subretinal space. This research could serve as a valuable resource for clinicians, offering guidance on the use of retinal imaging findings to support informed and effective treatment planning (Fig. 6).

Fig. 6.

Algorithm depicting the role of retinal imaging in submacular hemorrhage (SMH) for predicting treatment success

In summary, FAF, in conjunction with CFP and OCT in patients with SMH may offer valuable insights for clinicians when designing treatment strategies to optimize the effectiveness of treatment.

Abbreviations

SMH

Submacular haemorrhage

FAF

Fundus autofluorescence

OCT

Optical coherence tomography

CFP

Colour fundus photograph

tpA

Tissue plasminogen activator

PD

Pneumatic displacement

VEGF

Vascular endothelial growth factor

Author contributions

RV, JC – conceptualising the study, data acquisition, analysing the data, statistics and results, interpreting the findings, writing & reviewing the manuscriptAJ, SPC, AC, RM, ISA – Data acquisition and analysing the data NKY, SB, VP, RK – critically reviewing the manuscript.

Funding

No funds, grants or other supports was received.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics approval and consent to participate

All experimental protocols were approved by an institutional research committee (Narayana Nethralaya institutional review board – (C-2023-09-003). All methods were carried out in accordance with relevant guidelines and regulations (e.g. Declaration of Helsinki). Informed consent was obtained from all subjects (> 16 years) or from their legal guardian(s) (≤ 16years).

Consent for publication

Not applicable.

Animal research

“This article does not contain any studies with animals performed by any of the authors.”

Competing interests

The authors declare no competing interests.