Solar Eclipse

Experts from the MCPHS School of Optometry Share How to Safely View the Solar Eclipse on August 21

August 02, 2017

  • On August 21, 2017, a section of the United States, from South Carolina through Oregon, will experience a total solar eclipse as the sun tracks from west to east. The event is being called the “Great American Total Solar Eclipse,” and will darken skies and cause the temperature to drop rapidly, as the sun disappears behind the moon.

    Skywatchers outside of the path of totality, including those in Massachusetts and New Hampshire, will see a partial solar eclipse, in which the moon appears to cover part of the sun’s disk.

    With this beautiful sight comes an important reminder from experts at the School of Optometry at Massachusetts College of Pharmacy and Health Sciences (MCPHS): Never look at a partial solar eclipse without proper eye protection.

    Faculty members Hank VanVeen, OD and Larry Baitch OD, PhD shared insight into the proper ways to view the eclipse.

    “A solar eclipse is a truly awesome phenomenon to experience,” said Dr. VanVeen. “Even the most jaded of individuals cannot help but to feel moved when they observe the moon slowly obscure the sun, see day turned to twilight, and the emergence of stars in the sky.”

    "Using these tips will allow you to see the eclipse safely, and enjoy a truly memorable experience," said Dr. Baitch.

    When will the solar eclipse be visible?

    Here in Worcester, MA, where the School of Optometry is located, the eclipse will be partial, with the moon blocking 64% of the sun. The partial eclipse will start at 1:27 p.m and last until 4:00 p.m.

    What happens if I view a solar eclipse without special eye protection?

    According to optometrists Dr. VanVeen and Dr. Baitch, an eclipse is rare and beautiful, but is certainly not worth risking your vision permanently.

    Viewing of the eclipse, whether total or partial, requires special eye protection to avoid permanent damage to the central retina, the sensitive nerve layer of the eye. Solar retinopathy is the permanent damage caused by the intense ultraviolet and infrared light focused on the central retina.

    To get a sense of this type of damage, Dr. VanVeen and Dr. Baitch recommend thinking about how focusing the sun’s rays through a magnifying glass to a point on your skin can cause a painful burn. So too, the optics of the eye can focus the sun’s rays to a pinpoint on the retina, causing similar, but permanent, damage. Even in eclipse totality, the rays of the sun which reach around the edges of the moon can cause this destructive effect on the eye. The effect of solar retinopathy is the creation of a blind area in the very center, and most high-resolution part, of the visual field.

    How can I safely view the solar eclipse?

    According to Dr. VanVeen and Dr. Baitch, homemade filters or ordinary sunglasses, even dark ones, are not safe for looking at the solar eclipse.

    But, these experts outlined the many safe ways to view an eclipse:

    Projection

    The safest way to view the sun with binoculars or a telescope is by projection — looking at an image of the sun rather than at the sun itself. This method enables many people to view the sun simultaneously. You will need a pair of binoculars or a small telescope, a piece of plain cardboard of about 12 inches square for the "collar,'' and a second piece of white cardboard (or paper) of at least 4 inches square for the screen. If you use a telescope, you should mount it on a tripod. If you use binoculars, a stand or tripod will produce a steadier image. Click here to see a diagram of the telescope projection method.

    Pinhole projection

    There are many ways to project the view of the eclipse using a pinhole. However, the easiest method is to simply create a smooth, round hole with a diameter of approximately 1 mm (about 3/64 of an inch) in an index card. With the sun behind your shoulder, hold the card so that the sun shines on it at a 90 degree angle. Hold a second card about arms’ length in line with the pinhole card and the sun, and you will see the image of the eclipse projected upon the second card. The further the second card is from the pinhole card, the larger the image of the projection. Click here to see a diagram of a pinhole projection.

    Special solar filter glasses

    These filters allow safe viewing of the eclipse because they filter the harmful rays of the sun. Only use solar filter glasses that have met the standards of the American Optometric Association, the American Academy of Optometry, the American Academy of Ophthalmology and NASA. Dr. VanVeen and Dr. Baitch recommend solar filter glasses from Rainbow Symphony, American Paper Optics, TSE 17, and Thousand Oaks Optical.

    Dr. VanVeen and Dr. Baitch also advise skywatchers to never use a camera, telescope, binoculars or any optical device while using special solar filter glasses.

    Telescope and solar filters

    Any filter in front of the eye, whether used with a telescope or other optical instrument, should be placed in front of the optics - between the sun and the viewing instrument, say Dr. VanVeen and Dr. Baitch. On a telescope, for example, the filter should be placed in front of the lens closest to the sun. The filter must have a label clearly stating that it is in compliance with ISO 12312-2, which is the industry standard for allowing safe viewing of the sun.

    The School of Optometry at Massachusetts College of Pharmacy and Health Sciences (MCPHS) offers a four-year, full-time Doctor of Optometry program designed to prepare students with the requisite skills, experience, and confidence to practice and advance as a professional optometrist in a wide variety of clinical settings.