Limits...
The fundus slit lamp.

Gellrich MM - Springerplus (2015)

Bottom Line: The three lenses +90/+60/+40D are a good choice for imaging the whole spectrum of retinal diseases.A reconstruction of larger fundus areas is feasible for imaging in vitreoretinal surgery or occlusive vessel disease.Even a basic fundus controlled perimetry is possible.

View Article: PubMed Central - PubMed

Affiliation: Ophthalmological practice, Ziegeleiweg 10, 25548 Kellinghusen, Germany.

ABSTRACT
Fundus biomicroscopy with the slit lamp as it is practiced widely nowadays was not established until the 1980-es with the introduction of the Volk lenses +90 and +60D. Thereafter little progress has been made in retinal imaging with the slit lamp. It is the aim of this paper to fully exploit the potential of a video slit lamp for fundus documentation by using easily accessible additions. Suitable still images are easily retrieved from videorecordings of slit lamp examinations. The effects of changements in the slit lamp itself (slit beam and apertures) and its examination equipment (converging lenses from +40 to +90D) on quality and spectrum of fundus images are demonstrated. Imaging software is applied for reconstruction of larger fundus areas in a mosaic pattern (Hugin®) and to perform the flicker test in order to visualize changes in the same fundus area at different points of time (Power Point®). The three lenses +90/+60/+40D are a good choice for imaging the whole spectrum of retinal diseases. Displacement of the oblique slit light can be used to assess changes in the surface profile of the inner retina which occurs e.g. in macular holes or pigment epithelial detachment. The mosaic function in its easiest form (one strip macula adapted to one strip with the optic disc) provides an overview of the posterior pole comparable to a fundus camera's image. A reconstruction of larger fundus areas is feasible for imaging in vitreoretinal surgery or occlusive vessel disease. The flicker test is a fine tool for monitoring progressive glaucoma by changes in the optic disc, and it is also a valuable diagnostic tool in macular disease. Nearly all retinal diseases can be imaged with the slit lamp - irrespective whether they affect the posterior pole, mainly the optic nerve or the macula, the whole retina or only its periphery. Even a basic fundus controlled perimetry is possible. Therefore fundus videography with the slit lamp is a worthwhile approach especially for the many ophthalmologists without access to the most recent diagnostic equipment or a professional photographer at hand.

No MeSH data available.


Related in: MedlinePlus

Comparison between fundus photography and slit lamp videography for a right eye with macular hole and epiretinal membrane (here at same magnification, but original images captured at the settings given below - all figures in this article inverted as seen through the slit lamp). Top left: 50° posterior pole image - taken with a fundus camera (Zeiss, FF 450, dilated pupil, image inverted for comparison with slit lamp imaging).- Top right: Attempt to capture the pathological process in only one video image taken with the slit lamp (+90D lens, 12x magnification, slit wide open, white light). This image suffers from poor contrast. Reflexes which often disturb slit lamp fundus images are minor in this case. - Bottom left: Mosaic arrangement of 3 video images taken with the slit lamp (+90D lens, 20x magnification, green light) showing the clinically relevant area within the temporal vessel arcade. Single images were arranged with the program Hugin® and further processed with Power Point®. Disease-related features (macular hole, epiretinal membrane) stand out at greater contrast than in the classic fundus photograph top left. - Bottom right: showing the fundus area illuminated by projecting a 3.5 mm circular aperture on the fundus through different fundus lenses (from outer to inner black ring - the higher the lens power, the larger the illuminated fundus area - for comparison see Figure 3). By applying magnification factors given for the respective lenses in a schematic eye (see text) the ring diameters are 4.7 mm (+90D lens), 3.1 mm (+60D lens) and 2.1 mm (+40D lens) and their relation is 2.25 : 1.5 : 1.0. The white ring indicates a circle of 3.5 mm diameter on the retina.
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Fig2: Comparison between fundus photography and slit lamp videography for a right eye with macular hole and epiretinal membrane (here at same magnification, but original images captured at the settings given below - all figures in this article inverted as seen through the slit lamp). Top left: 50° posterior pole image - taken with a fundus camera (Zeiss, FF 450, dilated pupil, image inverted for comparison with slit lamp imaging).- Top right: Attempt to capture the pathological process in only one video image taken with the slit lamp (+90D lens, 12x magnification, slit wide open, white light). This image suffers from poor contrast. Reflexes which often disturb slit lamp fundus images are minor in this case. - Bottom left: Mosaic arrangement of 3 video images taken with the slit lamp (+90D lens, 20x magnification, green light) showing the clinically relevant area within the temporal vessel arcade. Single images were arranged with the program Hugin® and further processed with Power Point®. Disease-related features (macular hole, epiretinal membrane) stand out at greater contrast than in the classic fundus photograph top left. - Bottom right: showing the fundus area illuminated by projecting a 3.5 mm circular aperture on the fundus through different fundus lenses (from outer to inner black ring - the higher the lens power, the larger the illuminated fundus area - for comparison see Figure 3). By applying magnification factors given for the respective lenses in a schematic eye (see text) the ring diameters are 4.7 mm (+90D lens), 3.1 mm (+60D lens) and 2.1 mm (+40D lens) and their relation is 2.25 : 1.5 : 1.0. The white ring indicates a circle of 3.5 mm diameter on the retina.

Mentions: While in traditional fundus photography largely white light is applied to the fundus we find that green light gives better contrast to many fundus structures as epiretinal membranes, vessels and the fovea (Figure 2). If those settings which aim to capture a large fundus area in one picture are applied from fundus photography to slit lamp videography the results will be disappointing with degradation of the image: If image resolution is an important point slit lamp magnifications less than 12x (Gellrich 2009b) and lenses with higher power than the +90D lens (Volk 1986; Lee 1990) should not be used. An exception is if panretinal mosaics are to be created.Figure 2


The fundus slit lamp.

Gellrich MM - Springerplus (2015)

Comparison between fundus photography and slit lamp videography for a right eye with macular hole and epiretinal membrane (here at same magnification, but original images captured at the settings given below - all figures in this article inverted as seen through the slit lamp). Top left: 50° posterior pole image - taken with a fundus camera (Zeiss, FF 450, dilated pupil, image inverted for comparison with slit lamp imaging).- Top right: Attempt to capture the pathological process in only one video image taken with the slit lamp (+90D lens, 12x magnification, slit wide open, white light). This image suffers from poor contrast. Reflexes which often disturb slit lamp fundus images are minor in this case. - Bottom left: Mosaic arrangement of 3 video images taken with the slit lamp (+90D lens, 20x magnification, green light) showing the clinically relevant area within the temporal vessel arcade. Single images were arranged with the program Hugin® and further processed with Power Point®. Disease-related features (macular hole, epiretinal membrane) stand out at greater contrast than in the classic fundus photograph top left. - Bottom right: showing the fundus area illuminated by projecting a 3.5 mm circular aperture on the fundus through different fundus lenses (from outer to inner black ring - the higher the lens power, the larger the illuminated fundus area - for comparison see Figure 3). By applying magnification factors given for the respective lenses in a schematic eye (see text) the ring diameters are 4.7 mm (+90D lens), 3.1 mm (+60D lens) and 2.1 mm (+40D lens) and their relation is 2.25 : 1.5 : 1.0. The white ring indicates a circle of 3.5 mm diameter on the retina.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Fig2: Comparison between fundus photography and slit lamp videography for a right eye with macular hole and epiretinal membrane (here at same magnification, but original images captured at the settings given below - all figures in this article inverted as seen through the slit lamp). Top left: 50° posterior pole image - taken with a fundus camera (Zeiss, FF 450, dilated pupil, image inverted for comparison with slit lamp imaging).- Top right: Attempt to capture the pathological process in only one video image taken with the slit lamp (+90D lens, 12x magnification, slit wide open, white light). This image suffers from poor contrast. Reflexes which often disturb slit lamp fundus images are minor in this case. - Bottom left: Mosaic arrangement of 3 video images taken with the slit lamp (+90D lens, 20x magnification, green light) showing the clinically relevant area within the temporal vessel arcade. Single images were arranged with the program Hugin® and further processed with Power Point®. Disease-related features (macular hole, epiretinal membrane) stand out at greater contrast than in the classic fundus photograph top left. - Bottom right: showing the fundus area illuminated by projecting a 3.5 mm circular aperture on the fundus through different fundus lenses (from outer to inner black ring - the higher the lens power, the larger the illuminated fundus area - for comparison see Figure 3). By applying magnification factors given for the respective lenses in a schematic eye (see text) the ring diameters are 4.7 mm (+90D lens), 3.1 mm (+60D lens) and 2.1 mm (+40D lens) and their relation is 2.25 : 1.5 : 1.0. The white ring indicates a circle of 3.5 mm diameter on the retina.
Mentions: While in traditional fundus photography largely white light is applied to the fundus we find that green light gives better contrast to many fundus structures as epiretinal membranes, vessels and the fovea (Figure 2). If those settings which aim to capture a large fundus area in one picture are applied from fundus photography to slit lamp videography the results will be disappointing with degradation of the image: If image resolution is an important point slit lamp magnifications less than 12x (Gellrich 2009b) and lenses with higher power than the +90D lens (Volk 1986; Lee 1990) should not be used. An exception is if panretinal mosaics are to be created.Figure 2

Bottom Line: The three lenses +90/+60/+40D are a good choice for imaging the whole spectrum of retinal diseases.A reconstruction of larger fundus areas is feasible for imaging in vitreoretinal surgery or occlusive vessel disease.Even a basic fundus controlled perimetry is possible.

View Article: PubMed Central - PubMed

Affiliation: Ophthalmological practice, Ziegeleiweg 10, 25548 Kellinghusen, Germany.

ABSTRACT
Fundus biomicroscopy with the slit lamp as it is practiced widely nowadays was not established until the 1980-es with the introduction of the Volk lenses +90 and +60D. Thereafter little progress has been made in retinal imaging with the slit lamp. It is the aim of this paper to fully exploit the potential of a video slit lamp for fundus documentation by using easily accessible additions. Suitable still images are easily retrieved from videorecordings of slit lamp examinations. The effects of changements in the slit lamp itself (slit beam and apertures) and its examination equipment (converging lenses from +40 to +90D) on quality and spectrum of fundus images are demonstrated. Imaging software is applied for reconstruction of larger fundus areas in a mosaic pattern (Hugin®) and to perform the flicker test in order to visualize changes in the same fundus area at different points of time (Power Point®). The three lenses +90/+60/+40D are a good choice for imaging the whole spectrum of retinal diseases. Displacement of the oblique slit light can be used to assess changes in the surface profile of the inner retina which occurs e.g. in macular holes or pigment epithelial detachment. The mosaic function in its easiest form (one strip macula adapted to one strip with the optic disc) provides an overview of the posterior pole comparable to a fundus camera's image. A reconstruction of larger fundus areas is feasible for imaging in vitreoretinal surgery or occlusive vessel disease. The flicker test is a fine tool for monitoring progressive glaucoma by changes in the optic disc, and it is also a valuable diagnostic tool in macular disease. Nearly all retinal diseases can be imaged with the slit lamp - irrespective whether they affect the posterior pole, mainly the optic nerve or the macula, the whole retina or only its periphery. Even a basic fundus controlled perimetry is possible. Therefore fundus videography with the slit lamp is a worthwhile approach especially for the many ophthalmologists without access to the most recent diagnostic equipment or a professional photographer at hand.

No MeSH data available.


Related in: MedlinePlus